U.S. patent application number 12/213516 was filed with the patent office on 2008-12-25 for control device for vehicle power transmission device.
This patent application is currently assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA. Invention is credited to Masakazu Kaifuku, Tooru Matsubara, Atsushi Tabata.
Application Number | 20080318727 12/213516 |
Document ID | / |
Family ID | 40137078 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080318727 |
Kind Code |
A1 |
Matsubara; Tooru ; et
al. |
December 25, 2008 |
Control device for vehicle power transmission device
Abstract
A control device for a vehicle power transmission device
including an electrical differential motion portion in which a
differential state between input shaft rotation speed and output
shaft rotation speed is controlled through control of the operation
state of an electric motor linked to a rotating element of a
differential motion portion, and a power connection-disconnection
device constituting a portion of a power transmission path,
includes a controller that lessens a transmission capacity of the
power connection-disconnection device if during a switch of the
state of the vehicle power transmission device from a non-driving
state to a driving state, a change in input torque to the vehicle
power transmission device occurs, in comparison with when the
change in the input torque does not occur. Therefore, the control
device reduces the shift shock when the vehicle power transmission
device is switched from the non-driving to the driving state.
Inventors: |
Matsubara; Tooru;
(Toyota-shi, JP) ; Tabata; Atsushi; (Okazaki-shi,
JP) ; Kaifuku; Masakazu; (Okazaki-shi, JP) |
Correspondence
Address: |
OLIFF & BERRIDGE, PLC
P.O. BOX 320850
ALEXANDRIA
VA
22320-4850
US
|
Assignee: |
TOYOTA JIDOSHA KABUSHIKI
KAISHA
TOYOTA-SHI
JP
AISIN AW CO., LTD.
ANJO-SHI
JP
|
Family ID: |
40137078 |
Appl. No.: |
12/213516 |
Filed: |
June 20, 2008 |
Current U.S.
Class: |
477/3 |
Current CPC
Class: |
B60W 2510/0638 20130101;
Y10T 477/26 20150115; F16H 2312/02 20130101; B60L 2240/445
20130101; B60W 2510/068 20130101; Y02T 10/6239 20130101; B60K 1/02
20130101; B60L 2240/441 20130101; B60W 2510/246 20130101; B60W
2520/105 20130101; F16H 2200/2012 20130101; B60W 2530/10 20130101;
B60Y 2400/435 20130101; B60W 10/06 20130101; B60W 2510/244
20130101; F16H 2037/0873 20130101; F16H 2200/2043 20130101; Y02T
10/62 20130101; B60K 6/365 20130101; B60K 6/547 20130101; B60W
2510/0685 20130101; B60W 2510/0676 20130101; Y10T 477/23 20150115;
F16H 3/728 20130101; B60K 6/445 20130101; B60W 2540/16 20130101;
F16H 61/0437 20130101; B60L 2240/485 20130101; B60W 2520/10
20130101; Y02T 10/642 20130101; B60L 2240/486 20130101; B60W 20/10
20130101; B60W 2540/10 20130101; B60W 2510/107 20130101; B60W 20/00
20130101; B60W 2520/28 20130101; B60W 2540/12 20130101; B60W
2510/081 20130101; B60L 2240/421 20130101; B60W 10/115 20130101;
F16H 2312/14 20130101; Y02T 10/6286 20130101; F16H 2200/0043
20130101; Y02T 10/64 20130101; B60W 10/08 20130101; F16H 2061/0488
20130101; F16H 2061/0485 20130101 |
Class at
Publication: |
477/3 |
International
Class: |
B60W 10/10 20060101
B60W010/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 20, 2007 |
JP |
2007-163174 |
Claims
1. A control device for a vehicle power transmission device
including an electrical differential motion portion in which a
differential state between an input shaft rotation speed and an
output shaft rotation speed is controlled through control of an
operation state of an electric motor linked to a rotating element
of a differential motion portion, and a power
connection-disconnection device constituting a portion of a power
transmission path, comprising a controller that lessens a
transmission capacity of the power connection-disconnection device
if during a switch of a state of the vehicle power transmission
device from a non-driving state to a driving state, a change in
input torque to the vehicle power transmission device occurs, in
comparison with when the change in the input torque does not
occur.
2. The control device according to claim 1, wherein the change in
the input torque is due to start-up of an engine.
3. The control device according to claim 1, wherein the change in
the input torque is due to stop of an engine.
4. The control device according to claim 1, wherein the change in
the input torque is due to a charging control of an electricity
storage device.
5. The control device according to claim 1, wherein the change in
the input torque is due to a discharging control of an electricity
storage device.
6. The control device according to claim 1, further comprising a
vehicle start intention determination device that determines degree
of a driver's intention to start a vehicle, wherein if the degree
of the driver's intention to start the vehicle determined by the
vehicle start intention determination device is low, the controller
lessens the transmission capacity of the power
connection-disconnection device when the change in the input torque
to the vehicle power transmission device occurs during the switch
of the state of the vehicle power transmission device from the
non-driving state to the driving state in comparison with when the
change in the input torque does not occur.
7. The control device according to claim 1, further comprising a
vehicle speed-related value detection device that detects a vehicle
speed-related value regarding vehicle speed of a vehicle, wherein
if the vehicle speed-related value detected by the vehicle
speed-related value detection device is less than or equal to a
predetermined value, the controller lessens the transmission
capacity of the power connection-disconnection device when the
change in the input torque to the vehicle power transmission device
occurs during the switch of the state of the vehicle power
transmission device from the non-driving state to the driving state
in comparison with when the change in the input torque does not
occur.
8. The control device according to claim 1, wherein the electrical
differential motion portion operates as a continuously variable
transmission when the operation state of the electric motor is
controlled.
9. The control device according to claim 1, wherein the vehicle
power transmission device comprises a ratio shift portion that
constitutes a portion of the power transmission path, and the power
connection-disconnection device is an engagement element that
constitutes the ratio shift portion.
10. The control device according to claim 9, wherein the ratio
shift portion is a stepped ratio transmission.
11. A control device for a vehicle power transmission device
including an electrical differential motion portion in which a
differential state between an input shaft rotation speed and an
output shaft rotation speed is controlled through control of an
operation state of an electric motor linked to a rotating element
of a differential motion portion, and a power
connection-disconnection device constituting a portion of a power
transmission path, comprising a controller that delays start of
connection by the power connection-disconnection device if during a
switch of a state of the vehicle power transmission device from a
non-driving state to a driving state, a change in input torque to
the vehicle power transmission device occurs, in comparison with
when the change in the input torque does not occur.
12. The control device according to claim 11, wherein the change in
the input torque is due to start-up of an engine.
13. The control device according to claim 11, wherein the change in
the input torque is due to stop of an engine.
14. The control device according to claim 11, wherein the change in
the input torque is due to a charging control of an electricity
storage device.
15. The control device according to claim 11, wherein the change in
the input torque is due to a discharging control of an electricity
storage device.
16. The control device according to claim 11, further comprising a
vehicle start intention determination device that determines degree
of a driver's intention to start a vehicle, wherein if the degree
of the driver's intention to start the vehicle determined by the
vehicle start intention determination device is low, the controller
delays start of connection by the power connection-disconnection
device in a case where the change in the input torque to the
vehicle power transmission device occurs during the switch of the
state of the vehicle power transmission device from the non-driving
state to the driving state, in comparison with when the change in
the input torque does not occur.
17. The control device according to claim 11, further comprising a
vehicle speed-related value detection device that detects a vehicle
speed-related value regarding vehicle speed of a vehicle, wherein
if the vehicle speed-related value detected by the vehicle
speed-related value detection device is less than or equal to a
predetermined value, the controller delays start of connection by
the power connection-disconnection device in a case where the
change in the input torque to the vehicle power transmission device
occurs during the switch of the state of the vehicle power
transmission device from the non-driving state to the driving
state, in comparison with when the change in the input torque does
not occur.
18. The control device according to claim 11, wherein the
electrical differential motion portion operates as a continuously
variable transmission when the operation state of the electric
motor is controlled.
19. The control device according to claim 11, wherein the vehicle
power transmission device comprises a ratio shift portion that
constitutes a portion of the power transmission path, and the power
connection-disconnection device is an engagement element that
constitutes the ratio shift portion.
20. The control device according to claim 19, wherein the ratio
shift portion is a stepped ratio transmission.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2007-163174 filed on Jun. 20, 2007, including the specification,
drawings and abstract is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a vehicle power transmission device
and, more particularly, to a technology of reducing the shock that
occurs when the vehicle power transmission device is switched from
a non-driving state to a driving state.
[0004] 2. Description of the Related Art
[0005] There is a known vehicle power transmission device that
includes an electrical differential motion portion in which the
differential state between the input shaft rotation speed and the
output shaft rotation speed is controlled through the control of
the operation state of an electric motor linked to a rotating
element of a differential motion portion, and a power
connection-disconnection device that constitutes a portion of a
power transmission path. This vehicle power transmission device is
used together with, for example, an engine as a motive power
source, to realize a hybrid vehicle.
[0006] Through the control of the operation state of the electric
motor linked to the rotating element of the electrical differential
motion portion, the electrical differential motion portion can be
caused to operate in various manners, that is, to output the power
supplied to the input shaft from the engine provided as a motive
power source directly to the output shaft, or to convert the whole
or a portion of the power supplied from the engine into electric
energy by using the electric motor as a generator, or to output the
power generated by the electric motor alone or together with the
power supplied from the engine to the output shaft.
[0007] On the other hand, the power connection-disconnection device
can be used, for example, in a power transmission device, such as a
clutch which is provided, on a power transmission path; a ratio
shift portion whose speed change ratio can be changed; a stepped
automatic transmission in which a plurality of speed change steps
of different speed change ratios can be established by controlling
the engagement and release of the engagement elements, such as
clutches, brakes, etc.; a continuously variable transmission of a
belt type, a toroidal type, etc., which includes a forward-reverse
travel switch-over mechanism and whose speed change ratio is
continuously changed, etc. Specifically, such a ratio shift portion
is normally designed so that the ratio shift portion is switched
between a non-driving state in which power transmission is cut off,
such as the N (neutral) state, the P (parking) state, etc., and a
driving state in which power transmission is performed, such as the
D (drive) state, the R (reverse) state, etc. and the switching
between the foregoing states is carried out in accordance with a
driver's switching operation on a transmission state switch device
that includes, for example, a shift lever, a manual shift valve,
etc. Then, the power connection-disconnection device connects or
disconnects the power transmission, whereby the ratio shift portion
is switched between the non-driving state and the driving state,
and therefore the vehicle power transmission device as a whole is
also switched between the non-driving state and the driving
state.
[0008] If the state of a motive power source changes when the
vehicle power transmission device is switched from the non-driving
state to the driving state, there is possibility that the switching
to the driving state may not be smoothly carried out or a shift
shock may occur. Against this problem, Japanese Patent No. 3346375
discloses a technology of reducing the shift shock by keeping fixed
the states of output of the motive power source and the electric
motor during the switch of the ratio shift portion from the
non-driving state to the driving state.
[0009] By the way, according to the hybrid vehicle employing a
vehicle power transmission device as described above, the vehicle
is run while the engine as a motive power source is kept in an
optimum differential state through the control of the operation
state of the electric motor linked to the rotating element of the
differential motion portion. However, during a low engine
efficiency state, for example, when the vehicle is started from a
halt state, or the like, the vehicle is run only by the electric
motor. Therefore, during the state in which the vehicle is at a
stop or the vehicle speed is low, power is not supplied from the
engine but is supplied only from the electric motor at the time of
a shift operation in which the ratio shift portion is switched from
the non-driving state to the driving state, that is, at the time of
a garage shift, for example, the N.fwdarw.D shift, the N.fwdarw.R
shift, the P.fwdarw.R shift, etc.
[0010] However, if the state of charge (SOC) of the electricity
storage device provided in the vehicle is low, the engine needs to
be driven in order to generate electric power for charging the
electricity storage device. Besides, the engine is also driven
during the state where warm-up is needed. Such driving of the
engine is sometimes performed regardless of the situation of run of
the vehicle since the power thereby generated is not for use for
running the vehicle. In the case where the foregoing driving of the
engine is performed when the ratio shift portion is switched from
the non-driving state to the driving state, there is possibility of
a change occurring in the input torque to the vehicle driving
device and therefore a shift shock being caused.
SUMMARY OF THE INVENTION
[0011] The invention has been accomplished against the background
of the aforementioned circumstances, and provides a control device
in a vehicle power transmission device that includes an electrical
differential motion portion and a power connection-disconnection
device, the control device being capable of reducing the shift
shock when the vehicle power transmission device is switched from
the non-driving state to the driving state.
[0012] According to one aspect of the invention, there is provided
a control device for a vehicle power transmission device including
an electrical differential motion portion in which a differential
state between an input shaft rotation speed and an output shaft
rotation speed is controlled through control of an operation state
of an electric motor linked to a rotating element of a differential
motion portion, and a power connection-disconnection device
constituting a portion of a power transmission path. The control
device includes a controller that lessens a transmission capacity
of the power connection-disconnection device if during a switch of
a state of the vehicle power transmission device from a non-driving
state to a driving state, a change in input torque to the vehicle
power transmission device occurs, in comparison with when the
change in the input torque does not occur.
[0013] According to the control device for the vehicle power
transmission device, in the case where a change in the input torque
to the vehicle power transmission device occurs during a switch of
the state of the vehicle power transmission device from the
non-driving state to the driving state, the transmission capacity
of the power connection-disconnection device is lessened in
comparison with when the change in the input torque does not occur.
Therefore, the transmission capacity of the power
connection-disconnection device during a transitional state
occurring at the start of connection of the power is changed
according to changes in the input torque. Hence, the shift shock
can be reduced even in the case where the input torque to the
vehicle power transmission device changes during the switch of the
state of the vehicle power transmission device from the non-driving
state to the driving state.
[0014] According to another aspect of the invention, there is
provided a control device for a vehicle power transmission device
including an electrical differential motion portion in which a
differential state between an input shaft rotation speed and an
output shaft rotation speed is controlled through control of an
operation state of an electric motor linked to a rotating element
of a differential motion portion, and a power
connection-disconnection device constituting a portion of a power
transmission path. The control device includes a controller that
delays start of connection by the power connection-disconnection
device if during a switch of a state of the vehicle power
transmission device from a non-driving state to a driving state, a
change in input torque to the vehicle power transmission device
occurs, in comparison with when the change in the input torque does
not occur.
[0015] According to the control device for the vehicle power
transmission device, in the case where a change in the input torque
to the vehicle power transmission device occurs during a switch of
the state of the vehicle power transmission device from the
non-driving state to the driving state, the start of the connection
of power by the power connection-disconnection device is delayed in
comparison with the case where the change in the input torque does
not occur. Therefore, the engagement elements are engaged after the
change in the input torque has converged or has become diminished.
Hence, the shift shock can be reduced even in the case where the
input torque to the vehicle power transmission device changes
during the switch of the state of the vehicle power transmission
device from the non-driving state to the driving state.
[0016] The control device may further include a vehicle start
intention determination device that determines a vehicle start
intention determination device that determines degree of a driver's
intention to start a vehicle on the basis of accelerator operation
amount that corresponds to the amount of depression of an
accelerator pedal provided in the vehicle. With this construction,
the degree of the driver's intention to start the vehicle is
determined on the basis of the accelerator operation amount that
corresponds to the driver's requested drive force. Therefore, the
degree of the intention to start the vehicle that reflects the
driver's intention is determined.
[0017] Besides, the vehicle start intention determination device
may also determine the degree of the driver's intention to start
the vehicle on the basis of the state of a brake switch that
detects whether a brake pedal provided in the vehicle is being
operated. With this construction, the vehicle start intention
determination device can determine the case where the driver is
operating the brake pedal, that is, one of the cases where a shift
shock is likely to be perceived, as being a case where the degree
of the driver's intention to start the vehicle is low.
[0018] Besides, the vehicle start intention determination device
may determine the degree of the driver's intention to start the
vehicle on the basis of at least one of braking operation amounts,
for example, the output pressure of a brake master cylinder, the
depression force on a brake pedal, and the depression amount
(stroke) of the brake pedal. With this construction, the vehicle
start intention determination device determines the degree of the
driver's intention to start the vehicle on the basis of the braking
control amount, and therefore can determine the case where the
driver is performing a braking operation, that is, the case where
the shift shock is particularly likely to be perceived, as being a
case where the degree of the driver's intention to start the
vehicle is low.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The foregoing and further features and advantages of the
invention will be better understood by reading the following
detailed description of preferred embodiments of the invention,
when considered in connection with the accompanying drawings, in
which:
[0020] FIG. 1 is a skeleton diagram of a transmission mechanism
that constitutes a portion of a vehicle power transmission device
to which the invention is applied;
[0021] FIG. 2 is a operation diagram illustrating relations between
the speed change steps established in an automatic ratio shift
portion that constitutes the transmission mechanism shown in FIG. 1
and the operations of friction engagement devices employed in the
transmission mechanism;
[0022] FIG. 3 is an alignment chart illustrating the relative
rotation speeds of various gears in the transmission mechanism
shown in FIG. 1;
[0023] FIG. 4 is a diagram illustrating input/output signals of an
electronic control unit provided in an embodiment of the vehicle
power transmission device shown in FIG. 1;
[0024] FIG. 5 is a circuit diagram regarding linear solenoid valves
that control the operations hydraulic actuators of clutches and
brakes in a hydraulic control circuit;
[0025] FIG. 6 shows an example of a shift operation device provided
with a shift lever that is operated in order to select any one of a
plurality of kinds of shift positions;
[0026] FIG. 7 is a functional block diagram illustrating portions
of the control functions of the electronic control unit shown in
FIG. 4;
[0027] FIG. 8 is a diagram showing an example of a shift map used
in the ratio shift control of a driving device, and an example of s
drive force source map used in a drive force source switch control
of switching the travel of the vehicle between the engine travel
and the motor travel, and also showing relations therebetween;
[0028] FIG. 9 is an example of a fuel economy map, in which an
interrupted line is an optimum specific fuel consumption curve of
the engine;
[0029] FIG. 10 is a flowchart in a first embodiment of the
invention illustrating a control operation of the electronic
control unit shown in FIG. 4, that is, a control operation for
reducing the shift shock at the time of the switch of the automatic
ratio shift portion from the non-driving state to the driving
state;
[0030] FIG. 11 is a time chart in the first embodiment illustrating
the control operation shown in the flowchart of FIG. 10, in
conjunction with a case where a start-up control of the engine is
being performed in the case where a shift operation, for example,
from the N range to the D range, is performed;
[0031] FIG. 12 is a flowchart illustrating a control operation of
the electronic control unit in FIG. 4 in a second embodiment of the
invention, that is, a control operation for reducing the shift
shock at the time of the switch of the automatic ratio shift
portion from the non-driving state to the driving state, and
corresponds to FIG. 10;
[0032] FIG. 13 is a time chart illustrating the control operation
shown in the flowchart of FIG. 12 in the second embodiment, in
conjunction with a case where the start-up control of the engine s
being performed when a shift operation, for example, from the N
range to the D range, is performed; and
[0033] FIG. 14 is an example of a time chart representing
time-dependent changes of the command value of the engagement
pressure at the time of engagement of friction engagement element
devices of the automatic ratio shift portion in the case where the
invention is not applied.
DETAILED DESCRIPTION OF THE EMBODIMENTS
[0034] In the following description and the accompanying drawings,
the present invention will be described in greater detail with
reference to the example embodiments.
[0035] A first embodiment of the invention will be described in
detail with reference to the drawings. FIG. 1 is a skeleton diagram
illustrating a transmission mechanism 10 that constitutes a portion
of a power transmission device of a hybrid vehicle to which the
invention is applied. In FIG. 1, the transmission mechanism 10
includes an input shaft 14 as an input rotating member, a
differential motion portion 11 as a stepless ratio shift portion
that is linked directly to the input shaft 14 or indirectly thereto
via a pulsation absorbing damper (vibration damping device) (not
shown) or the like, an automatic ratio shift portion 20 as a power
transmission portion that is linked in series in the power
transmission path between the differential motion portion 11 and
driving wheels 34 (see FIG. 7) via a transmission member (power
transmission shaft) 18, and an output shaft 22 as an output
rotating member that is linked to the automatic ratio shift portion
20. These members of the transmission mechanism 10 are disposed on
a common center axis within a transmission case 12 (hereinafter,
referred to as "the case 12") provided as a non-rotating member
attached to a vehicle body. This transmission mechanism 10 is
suitably used in, for example, an FR (front engine, rear wheel
drive) type vehicle in which the mechanism 10 is longitudinally
mounted. The transmission mechanism 10 is provided between a pair
of driving wheels 34 and an internal combustion engine 8, for
example, a gasoline engine, a diesel engine, etc., provided as a
vehicle-running drive force source which is directly linked to the
input shaft 14 or indirectly linked thereto via a pulsation
absorbing damper (not shown). The transmission mechanism 10
transmits power from the engine 8 to the pair of driving wheels 34,
sequentially via differential gear device (final speed reducer) 32
(see FIG. 7), a pair of axle shafts, etc., which each form a
portion of the power transmission path.
[0036] In the transmission mechanism 10 of the first embodiment,
the engine 8 and the differential motion portion 11 are directly
coupled. Being directly coupled herein means being linked without
the intervention of a fluid type transmission device, such as a
torque converter, a fluid coupling, etc.; for example, the
aforementioned linkage via the pulsation absorbing damper or the
like is included in this direct coupling. Incidentally, the
transmission mechanism 10 is constructed symmetrically about its
axis, and in the skeleton diagram of FIG. 1, the lower half thereof
is omitted from illustration.
[0037] The differential motion portion 11 includes a first electric
motor M1, a power distribution mechanism 16 as a differential
mechanism which is a mechanical mechanism that mechanically
distributes the output of the engine 8 (hereinafter, referred to as
"the engine output") input to the input shaft 14 and which
distributes the engine output to the first electric motor M1 and
the transmission member 18, and a second electric motor M2 that is
operatively linked to the transmission member 18 so as to rotate
integrally with the transmission member 18. The first electric
motor M1 and the second electric motor M2 in the first embodiment
are so-called motor-generators that also have an electric power
generating function. Furthermore, the first electric motor M1 is
equipped at least with a generator (power generation) function for
generating a reaction force, and the second electric motor M2 is
equipped at least with a motor (electric motor) function for
outputting drive force as a vehicle-running drive force source.
[0038] The power distribution mechanism 16 is constructed mainly of
a single-pinion type first planetary gear device 24 that has a
predetermined gear ratio .rho.1 that is, for example, about 0.418.
The rotating elements (elements) of the first planetary gear device
24 include a first sun gear S1, first planetary gears P1, a first
carrier CA1 that supports the first planetary gears P1 so that each
of the first planetary gears P1 is rotatable about its own axis as
well as revolvable, and a first ring gear R1 that meshes with the
first sun gear S1 via the first planetary gears P1. If the number
of teeth of the first sun gear S1 is ZS1 and the number of teeth of
the first ring gear R1 is ZR1, the aforementioned gear ratio .rho.1
is ZS1/ZR1.
[0039] In the power distribution mechanism 16, the first carrier
CA1 is linked to the input shaft 14, that is, to the engine 8, and
the first sun gear S1 is linked to the first electric motor M1, and
the first ring gear R1 is linked to the transmission member 18.
Since the power distribution mechanism 16 is put into a state in
which differential motion can be performed, that is, a differential
state in which the differential motion occurs, as three of the
elements of the first planetary gear device 24, that is, the first
sun gear S1, the first carrier CA1 and the first ring gear R1, are
allowed to rotate relatively to each other, the engine output is
distributed between the first electric motor M1 and the
transmission member 18, and the electric energy that the first
electric motor M1 generates from a portion of the engine output
distributed thereto is electrically stored or is used to
rotationally drive the second electric motor M2. Thus, the
differential motion portion 11 (the power distribution mechanism
16) is caused to function as an electrical differential device; for
example, the differential motion portion 11 is put into a so-called
stepless or continuously variable transmission state (electrical
CVT state), in which the rotation of the transmission member 18 is
continuously changed despite a predetermined rotation speed of the
engine 8. That is, the differential motion portion 11 is an
electrical differential motion portion that functions as an
electrical continuously variable transmission whose speed change
ratio .gamma.0 (the rotation speed NIN of the input shaft 14/the
rotation speed N18 of the transmission member 18) is continuously
changed from a minimum value .gamma.0min to a maximum value
.gamma.0max.
[0040] The automatic ratio shift portion 20 is a planetary
gear-type multi-stepped-speed transmission that includes a
single-pinion type second planetary gear device 26, a single-pinion
type third planetary gear device 28 and a single-pinion type fourth
planetary gear device 30, and that functions as a
stepped-speed-type automatic transmission. The second planetary
gear device 26 includes a second sun gear S2, second planetary
gears P2, a second carrier CA2 supporting each of the second
planetary gears P2 rotatably about its own axis and also
revolvably, and a second ring gear R2 meshing with the second sun
gear S2 via the second planetary gears P2, and has a predetermined
gear ratio .rho.2 of, for example, about "0.562". The third
planetary gear device 28 includes a third sun gear S3, third
planetary gears P3, a third carrier CA3 supporting each of the
third planetary gears P3 rotatably about its own axis and also
revolvably, and a third ring gear R3 meshing with the third sun
gear S3 via the third planetary gears P3, and has a gear ratio
.rho.3 of, for example, about "0.425". The fourth planetary gear
device 30 includes a fourth sun gear S4, fourth planetary gears P4,
a fourth carrier CA4 supporting each of the fourth planetary gears
P4 about its own axis and also revolvably, and a fourth ring gear
R4 meshing with the fourth sun gear S4 via the fourth planetary
gears P4, and has a gear ratio .rho.4 of, for example, about
"0.421". If the number of teeth of the second sun gear S2 is ZS2
and the number of teeth of the second ring gear R2 is ZR2 and the
number of teeth of the third sun gear S3 is ZS3 and the number of
teeth of the third ring gear R3 is ZR3 and the number of teeth of
the fourth sun gear S4 is ZS4 and the number of teeth of the fourth
ring gear R4 is ZR4, then the aforementioned gear ratio .rho.2 is
ZS2/ZR2, and the aforementioned gear ratio .rho.3 is ZS3/ZR3, and
the gear ratio .rho.4 is ZS4/ZR4.
[0041] In the automatic ratio shift portion 20, the second sun gear
S2 and the third sun gear S3 are integrally interlinked, and are
selectively linked to the transmission member 18 via a second
clutch C2, and also is selectively linked to the case 12 via a
first brake B1. The second carrier CA2 is selectively linked to the
case 12 via a second brake B2, and the fourth ring gear R4 is
selectively linked to the case 12 via a third brake B3.
Furthermore, the second ring gear R2, the third carrier CA3 and the
fourth carrier CA4 are integrally interlinked, and are linked to
the output shaft 22. The third ring gear R3 and the fourth sun gear
S4 are integrally interlinked, and are selectively linked to the
transmission member 18 via a first clutch C1.
[0042] In this manner, the interior of the automatic ratio shift
portion 20 and the differential motion portion 11 (the transmission
member 18) are selectively interlinked via at least one of the
first clutch C1 and the second clutch C2, which are used to
establish gear steps (speed change steps) of the automatic ratio
shift portion 20. In other words, the first clutch C1 and the
second clutch C2 function as an engagement device that selectively
switches the power transmission path between the transmission
member 18 and the automatic ratio shift portion 20, that is, the
power transmission path from the differential motion portion 11
(the transmission member 18) to the driving wheels 34, between a
power transmission-capable state in which the power transmission
through the power transmission path is made possible, and a power
transmission cut-off state in which the power transmission through
the power transmission path is cut off. Specifically, as at least
one of the first clutch C1 and the second clutch C2 is engaged, a
driving state of the vehicle in which the foregoing power
transmission path is in the power transmission-capable state is
brought about. As both the first clutch C1 and the second clutch C2
are released, a non-driving state of the vehicle in which the power
transmission path is in the power transmission cut-off state is
brought about. That is, of the friction engagement elements of the
automatic ratio shift portion 20, at least the first clutch C1 and
the second clutch C2 correspond to power connection-disconnection
devices.
[0043] Besides, the automatic ratio shift portion 20 attains the
speed change ratio .gamma.(=the transmission member 18 of the
rotation speed N18/the output shaft 22 of the rotation speed NOUT)
that changes at substantially equal ratios for each gear step as
the clutch-to-clutch shift is carried out by the release of a
release-side engagement device and the engagement of an
engagement-side engagement device so as to selectively establish
each gear step. For example, as shown in the engagement operation
table of FIG. 2, the engagement of the first clutch C1 and of the
third brake B3 establishes a first speed gear step whose speed
change ratio .gamma.1 is the maximum value, for example, about
"3.357". The engagement of the first clutch C1 and of the second
brake B2 establishes a second-speed gear step whose speed change
ratio .gamma.2 is a value that is smaller than that of the first
speed gear step, for example, about "2.180", and the engagement of
the first clutch C1 and of the first brake B1 establishes a
third-speed gear step whose speed change ratio .gamma. is a value
that is smaller than that of the second-speed gear step, for
example, about "1.424", and the engagement of the first clutch C1
and of the second clutch C2 establishes a fourth-speed gear step
whose speed change ratio .gamma.4 is a value that is smaller than
that of the third-speed gear step, for example, about "1.000".
Besides, the engagement of the second clutch C2 or the third brake
B3 establishes a reverse travel gear step (reverse travel speed
change step) whose speed change ratio .gamma.R is a value that is
between that of the first speed gear step and that of the
second-speed gear step, for example, about "3.209". Besides, the
release of the first clutch C1, the second clutch C2, the first
brake B1, the second brake B2 and the third brake B3 brings about a
neutral "N" state.
[0044] The first clutch C1, the second clutch C2, the first brake
B1, the second brake B2 and the third brake B3 (hereinafter, termed
the clutches C and the brakes B if distinction thereof is not
particularly made) are hydraulic type friction engagement devices
as engagement elements that are often employed in related-art
vehicle automatic transmissions. The clutches C and the brakes B
are each made up of a wet multiplate clutch in which a plurality of
friction discs superposed on each other are pressurized against
each other by a hydraulic actuator, a band brake in which an end of
one or two bands wrapped around an outer peripheral surface of a
rotating drum is pulled tight by a hydraulic actuator, etc. Each of
the clutches C and the brakes B is provided for selectively linking
both side members between which it is disposed.
[0045] In the transmission mechanism 10 constructed as described
above, the differential motion portion 11 that functions as a
continuously variable transmission, and the automatic ratio shift
portion 20 make up a continuously variable transmission as a whole.
Besides, if the differential motion portion 11 is controlled so
that its speed change ratio remains constant, the differential
motion portion 11 and the automatic ratio shift portion 20 can make
up a device that is substantially the same as a stepped ratio
transmission.
[0046] Concretely, when the differential motion portion 11
functions as a continuously variable transmission and the automatic
ratio shift portion 20 connected in series to the differential
motion portion 11 functions as a stepped ratio transmission, the
rotation speed input to the automatic ratio shift portion 20
(hereinafter, referred to as the input rotation speed of the
automatic ratio shift portion 20) with respect to at least one
speed change step M of the automatic ratio shift portion 20, that
is, the rotation speed of the transmission member 18 (hereinafter,
referred to as "the transmission member rotation speed N18"), is
steplessly changed, so that a stepless speed change ratio width at
the speed change step M can be obtained. Therefore, the overall
speed change ratio .gamma.T of the transmission mechanism 10 (=the
input shaft 14 of the rotation speed NIN/the output shaft 22 of the
rotation speed NOUT) is steplessly obtained, and thus a
continuously variable transmission is constructed in the
transmission mechanism 10. The overall speed change ratio .gamma.T
of the transmission mechanism 10 is a total speed change ratio
.gamma.T of the transmission mechanism 10 as a whole which is
formed on the basis of the speed change ratio .gamma.0 of the
differential motion portion 11 and the speed change ratio .gamma.
of the automatic ratio shift portion 20.
[0047] For example, for each of the first to fourth gear steps and
the reverse travel gear step of the automatic ratio shift portion
20 shown in the engagement operation table of FIG. 2, the
transmission member rotation speed N18 is steplessly changed, so
that each gear step is provided with a stepless speed change ratio
width. Therefore, the speed change ratio is continuously variable
between the gear steps, so that the total speed change ratio
.gamma.T of the transmission mechanism 10 as a whole is steplessly
varied.
[0048] When the speed change ratio of the differential motion
portion 11 is controlled so as to be constant and the clutches C
and the brakes B are selectively engaged so as to selectively
establish one of the first to fourth speed gear steps and the
reverse travel gear step (reverse travel speed change step), the
total speed change ratios .gamma.T of the transmission mechanism 10
varying substantially at equal ratios of variation can be obtained
for the individual gear steps. Therefore, in the transmission
mechanism 10, a state that is substantially the same as that of a
stepped ratio transmission is formed.
[0049] For example, the speed change ratio .gamma.0 of the
differential motion portion 11 is controlled so as to be fixed at
"1", the total speed change ratios .gamma.T of the transmission
mechanism 10 corresponding to the individual ones of the first to
fourth speed gear steps and the reverse travel gear step of the
automatic ratio shift portion 20 as shown in the engagement
operation table of FIG. 2 can be obtained. Furthermore, if while
the fourth-speed gear step is selected in the automatic ratio shift
portion 20, the speed change ratio .gamma.0 of the differential
motion portion 11 is controlled so as to be fixed at a value
smaller than "1", for example, at about 0.7, a total speed change
ratio that is smaller than that of the fourth-speed gear step, for
example, a total speed change ratio of about "0.7", is
obtained.
[0050] FIG. 3 shows an alignment chart that represents on straight
lines the relationships among the rotation speeds of various
rotating elements varying in the state of linkage for the
individual gear steps in the transmission mechanism 10 that is
constructed of the differential motion portion 11 and the automatic
ratio shift portion 20. The alignment chart in FIG. 3 is of a
two-dimensional coordinate system made up of a horizontal axis that
shows relationships among the gear ratios .beta. of the planetary
gears devices 24, 26, 28, 30, and a vertical axis that shows
relative rotation speeds. In the chart, a horizontal line X1 shows
a rotation speed of zero, and a horizontal line X2 shows a rotation
speed of "1.0", which is the rotation speed NE of the engine 8
linked to the input shaft 14, and a horizontal line XG shows the
rotation speed of the transmission member 18.
[0051] Besides, three vertical lines Y1, Y2, Y3 corresponding to
three elements of the power distribution mechanism 16 constituting
the differential motion portion 11 show the relative rotation
speeds of the first sun gear S1 corresponding to a second rotating
element (second element) RE2, the first carrier CA1 corresponding
to a first rotating element (first element) RE1, and the first ring
gear R1 corresponding to a third rotating element (third element)
RE3, in that order from the left-hand side. The intervals between
the three vertical lines are determined according to the gear ratio
.rho.1 of the first planetary gear device 24. Furthermore, five
vertical lines Y4, Y5, Y6, Y7, Y8 regarding the automatic ratio
shift portion 20 represent the second sun gear S2 and the third sun
gear S3 that correspond to a fourth rotating element (fourth
element) RE4 and that are interlinked with each other, the second
carrier CA2 corresponding to a fifth rotating element (fifth
element) RE5, the fourth ring gear R4 corresponding to a sixth
rotating element (sixth element) RE6, the second ring gear R2, the
third carrier CA3 and the fourth carrier CA4 that correspond to a
seventh rotating element (seventh element) RE7 and that are
interlinked with each other, and the third ring gear R3 and the
fourth sun gear S4 that correspond to an eighth rotating element
(eighth element) RE8 and that are interlinked with each other,
respectively. The intervals between the vertical lines are
respectively determined according to the gear ratios .rho.2,
.rho.3, .rho.4 of the second, third and fourth planetary gear
devices 26, 28, 30. In the relationship among the vertical lines in
the alignment chart, if the interval between the sun gear and the
carrier is set at an interval corresponding to "1", the interval
between the carrier and the ring gear becomes an interval
corresponding to the gear ratio .rho. of the planetary gear device.
Specifically, in the differential motion portion 11, the interval
between the vertical line Y1 and the vertical line Y2 is set at an
interval that corresponds to "1", and the interval between the
vertical line Y2 and the vertical line Y3 is set at an interval
that corresponds to the gear ratio .rho.1. Besides, as for each of
the second, third and fourth planetary gear devices 26, 28, 30 of
the automatic ratio shift portion 20, the interval between the
vertical lines of the sun gear and the carrier is set at an
interval that corresponds to "1", and the interval between the
vertical lines of the carrier and the ring gear is set at an
interval that corresponds to .rho..
[0052] The transmission mechanism 10 of this first embodiment, if
described through the use of the alignment chart in FIG. 3, is
constructed as follows. That is, in the power distribution
mechanism 16 (the differential motion portion 11), the first
rotating element RE1 (the first carrier CA1) of the first planetary
gear device 24 is linked to the input shaft 14, that is, to the
engine 8, and the second rotating element RE2 is linked to the
first electric motor M1, and the third rotating element (the first
ring gear R1) RE3 is linked to the transmission member 18 and the
second electric motor M2, so that rotation of the input shaft 14 is
transmitted (input) to the automatic ratio shift portion 20 via the
transmission member 18. In conjunction with this construction, a
diagonal straight line L0 passing through the intersection point
between the line Y2 and the line X2 shows a relationship between
the rotation speed of the first sun gear S1 and the rotation speed
of the first ring gear R1.
[0053] For example, in the case where the differential motion
portion 11 is in a differential state in which the first to third
rotating elements RE1 to RE3 are rotatable relative to each other,
and the rotation speed of the first ring gear R1 shown by the
intersection point between the straight line L0 and the vertical
line Y3 is restricted to a vehicle speed V and is therefore
substantially constant, the rotation speed of the first sun gear S1
shown by the intersection point between the straight line L0 and
the vertical line Y1, that is, the rotation speed of the first
electric motor M1, becomes raised or lowered if the rotation speed
of the first carrier CA1 shown by the intersection point between
the straight line L0 and the vertical line Y2 is raised or lowered
by controlling the engine rotation speed NE.
[0054] Besides, if the rotation speed of the first sun gear S1 is
made equal to the engine rotation speed NE by controlling the
rotation speed of the first electric motor M1 so that the speed
change ratio .gamma.0 of the differential motion portion 11 becomes
fixed at "1", the straight line L0 comes to coincide with the
horizontal line X2, and the first ring gear R1 is rotated, that is,
the transmission member 18 is rotated, at the same rotation speed
as the engine rotation speed NE. Or, if the rotation speed of the
first sun gear S1 is made zero by controlling the rotation speed of
the first electric motor M1 so that the speed change ratio .gamma.0
of the differential motion portion 11 becomes fixed at a value
smaller than "1", for example, at about 0.7, the transmission
member rotation speed N18 is rotated at a rotation speed that is
greater than the engine rotation speed NE.
[0055] Besides, in the automatic ratio shift portion 20, the fourth
rotating element RE4 is selectively linked to the transmission
member 18 via the second clutch C2, and is also selectively linked
to the case 12 via the first brake B1, and the fifth rotating
element RE5 is selectively linked to the case 12 via the second
brake B2, and the sixth rotating element RE6 is selectively linked
to the case 12 via the third brake B3, and the seventh rotating
element RE7 is linked to the output shaft 22, and the eighth
rotating element RE8 is selectively linked to the transmission
member 18 via the first clutch C1.
[0056] In the automatic ratio shift portion 20, if with regard to
the differential motion portion 11, the straight line L0 is made to
coincide with the horizontal line X2 and therefore the rotation
speed equal to the engine rotation speed NE is input from the
differential motion portion 11 to the eighth rotating element RE8,
the first clutch C1 and the third brake B3 are engaged as shown in
FIG. 3, so that the rotation speed of the output shaft 22 at the
first speed (1st) is shown by the intersection point between the
vertical line Y7 showing the rotation speed of the seventh rotating
element RE7 linked to the output shaft 22 and the diagonal straight
line L1 passing through the intersection point between the
horizontal line X1 and the vertical line Y6 showing the rotation
speed of the sixth rotating element RE6 and also through the
intersection point between the horizontal line X2 and the vertical
line Y8 showing the rotation speed of the eighth rotating element
RE8. Likewise, the rotation speed of the output shaft 22 at the
second speed (2nd) is shown by the intersection point between the
vertical line Y7 showing the rotation speed of the seventh rotating
element RE7 linked to the output shaft 22 and a diagonal straight
line L2 determined by the engagement of the first clutch C1 and of
the second brake B2. The rotation speed of the output shaft 22 at
the third speed (3rd) is shown by the intersection point between
the vertical line Y7 showing the rotation speed of the seventh
rotating element RE7 linked to the output shaft 22 and a diagonal
straight line L3 determined by the engagement of the first clutch
C1 and of the first brake B1. The rotation speed of the output
shaft 22 at the fourth speed (4th) is shown by the intersection
point between the vertical line Y7 showing the rotation speed of
the seventh rotating element RE7 linked to the output shaft 22 and
a horizontal straight line L4 determined by the engagement of the
first clutch C1 and of the second clutch C2.
[0057] FIG. 4 shows an example of signals input to an electronic
control unit 80 for controlling the transmission mechanism 10 in
the first embodiment and signals output from the electronic control
unit 80. This electronic control unit 80 includes a so-called
microcomputer made up of a CPU, a ROM, a RAM, input/output
interfaces, etc. By performing signal processing in accordance with
programs pre-stored in the ROM while utilizing the temporary
storage function of the RAM, the electronic control unit 80
executes driving controls, such as hybrid drive controls regarding
the engine 8 and the first and second electric motors M1, M2, the
ratio shift control of the automatic ratio shift portion 20,
etc.
[0058] The electronic control unit 80 is supplied from various
sensors, switches, etc., with signals, including a signal
representing the engine coolant temperature TEMPW, a signal
representing the shift position PSH of a shift lever 52 (see FIG.
6), the number of times of operation at the "M" position, etc., a
signal representing the engine rotation speed NE, that is, the
rotation speed of the engine 8, a signal commanding an M mode
(manual shift travel mode), a signal representing the operation of
an airconditioner, a signal representing the rotation speed NOUT of
the output shaft 22 corresponding to the vehicle speed V
(hereinafter, referred to as "the output shaft rotation speed
NOUT"), a signal representing the temperature THATF of automatic
transmission fluid (hereinafter, referred to as "the ATF
temperature THATF") that is used for a control operation of the
automatic ratio shift portion 20, a signal representing the parking
brake operation, a signal representing a foot brake operation, a
signal representing the catalyst temperature, a signal representing
the accelerator operation amount Acc, that is, the amount of
operation of an accelerator pedal, which corresponds to a driver's
requested output amount, a signal representing the cam angle, a
signal representing the setting of a snow mode, a signal
representing the longitudinal acceleration G of the vehicle, a
signal representing the automatic cruise travel, a signal
representing the weight of the vehicle (vehicle weight), a signal
representing the wheel speed of each tire wheel, a signal
representing the rotation speed NM1 of the first electric motor M1
(hereinafter, referred to as "the first electric motor rotation
speed NM1"), a signal representing the rotation speed NM2 of the
second electric motor M2 (hereinafter, referred to as "the second
electric motor rotation speed NM2"), a signal representing the
charged capacity (state of charge) SOC of an electricity storage
device 56 (see FIG. 7), a signal representing the temperature of an
electricity storage device 56, a signal representing the brake
master cylinder pressure, that is, the output pressure of a brake
master cylinder 110, etc.
[0059] The electronic control unit 80 outputs various signals,
including control signals to an engine output control device 58
(see FIG. 7) that controls the engine output, for example, a drive
signal to a throttle actuator 64 that manipulates the throttle
valve opening degree .theta.TH of an electronic throttle valve 62
provided in an intake pipe 60 of the engine 8, a fuel supply amount
signal that controls the amount of fuel supplied by a fuel
injection device 66 into an intake pipe 60 or each cylinder of the
engine 8, or an ignition signal that commands the timing of the
ignition performed by an ignition device 68 in the engine 8, a
supercharge pressure adjustment signal for adjusting the
supercharge pressure, an electric air-conditioner drive signal for
operating an electric air-conditioner, a command signal that
commands the operation of the electric motors M1 and M2, a shift
position (operation position) display signal for operating a shift
indicator, a gear ratio display signal for displaying the gear
ratio, a snow mode display signal for displaying that the snow mode
is on, an ABS operation signal for operating an ABS actuator that
prevents slippage of wheels during braking, an M-mode display
signal that displays that the M mode has been selected, a valve
command signal that operates electromagnetic valves (linear
solenoid valves) that are included in a hydraulic control circuit
70 (see FIG. 5 and FIG. 7) in order to control the hydraulic
actuators of hydraulic type friction engagement devices provided
for the differential motion portion 11 or the automatic ratio shift
portion 20, a signal for adjusting a line oil pressure PL through
the use of a regulator valve (pressure regulating valve) provided
in the hydraulic control circuit 70, a drive command signal for
operating an electric hydraulic pump that is an oil pressure source
of a basic pressure from which the line oil pressure PL is
adjusted, a signal for driving an electric heater, a signal to a
computer for the cruise control, an output restraint information
signal for informing a driver that the output of the drive force
source (hereinafter, referred to as "the drive force source
output") is being restrained; for example, the engine output
(power) and/or the output of the second electric motor M2
(hereinafter, referred to as "the second electric motor output")
are being restrained, etc.
[0060] FIG. 5 is a hydraulic circuit diagram regarding linear
solenoid valves SL1 to SL5 that control the operations of hydraulic
actuators (hydraulic cylinders) AC1, AC2, AB1, AB2, AB3 of the
clutches C1, C2 and the brakes B1 to B3 in the hydraulic control
circuit 70.
[0061] In FIG. 5, the hydraulic actuators AC1, AC2, AB1, AB2, AB3
are directly supplied with engagement pressures PC1, PC2, PB1, PB2,
PB3, respectively, that are adjusted from the line oil pressure PL
by the linear solenoid valves SL1 to SL5 according to the command
signals from the electronic control unit 80. The line oil pressure
PL is adjusted by, for example, a relief-type pressure regulating
valve (regulator valve), from the basic pressure that is an oil
pressure produced by an electric oil pump (not shown) or a
mechanical oil pump (not shown) that is rotationally driven by the
engine 8, to a value according to the engine load or the like
represented by the accelerator operation amount Acc or the throttle
valve opening degree .theta.TH.
[0062] The linear solenoid valves SL1 to SL5 basically have the
same construction, and are independently energized or de-energized
by the electronic control unit 80 so that the oil pressures of the
hydraulic actuators AC1, AC2, AB1, AB2, AB3 are independently
adjusted and controlled to control the engagement pressures PC1,
PC2, PB1, PB2, PB3 of the clutches C1, C2 and the brakes B1, B2,
B3. Then, in the automatic ratio shift portion 20, predetermined
engagement devices are engaged, for example, as shown in the
engagement operation table of FIG. 2, to establish an appropriate
one of the speed change steps. Besides, in the ratio shift control
of the automatic ratio shift portion 20, for example, a so-called
clutch-to-clutch shift in which the release and the engagement of
the clutches C or brakes B involved in the ratio shift are
simultaneously controlled is executed.
[0063] FIG. 6 is a diagram showing an example of a shift operation
device 50 as a switch device for switching among a plural kinds of
shift positions PSH by manual operation. This shift operation
device 50 includes a shift lever 52 that is disposed, for example,
at a side of a driver's seat, and that is operated in order to
select an appropriate one of the plural kinds of shift positions
PSH.
[0064] The shift lever 52 is provided so as to be manually operated
to a parking position "P (Parking)" for bringing about a neutral
state in which the power transmission path in the transmission
mechanism 10, that is, in the automatic ratio shift portion 20, is
cut off, and for locking the output shaft 22 of the automatic ratio
shift portion 20, a reverse travel position "R (Reverse)" for
reverse travel, a neutral position "N (Neutral)" for bringing about
a neutral state in which the power transmission path in the
transmission mechanism 10 is cut off, a forward travel automatic
shift position "D (Drive)" for establishing an automatic shift mode
of executing an automatic ratio shift control within the range of
change of the total speed change ratio .gamma.T that can be
achieved by the transmission mechanism 10 from the stepless speed
change ratio width of the differential motion portion 11 and the
automatic shift-controlled gear steps, that is, the first to fourth
speed gear steps, of the automatic ratio shift portion 20, or a
forward travel manual shift position "M (Manual)" for establishing
a manual shift travel mode (manual mode) of setting a so-called
shift range that restricts the high speed-side speed change steps
in the automatic ratio shift control of the automatic ratio shift
portion 20.
[0065] In concert with the manual operation of the shift lever 52
to any of the shift positions PSH, the hydraulic control circuit
70, for example, is electrically switched so as to establish a
corresponding one of the reverse travel gear step "R", the neutral
"N", the various speed change steps of the forward travel gear
steps "D", etc.
[0066] Of the shift positions PSH shown as the "P" to "M" positions
in the above-description, the "P" position and the "N" position are
non-travel positions each of which is selected when the vehicle is
not to be run, and are also non-driving positions for selecting a
switch of the power transmission pathway to a power transmission
cut-off state based on the first clutch C1 and the second clutch C2
in which the vehicle cannot be driven as the power transmission
path in the automatic ratio shift portion 20 is cut off; that is,
both the first clutch C1 and the second clutch C2 are released, as
shown in the engagement operation table of FIG. 2. Besides, the "R"
position, the "D" position and the "M" position are travel
positions each of which is selected when the vehicle is to be run,
and are driving positions for selecting a switch of the power
transmission pathway to a power transmission-capable state based on
the first clutch C1 and/or the second clutch C2 in which the
vehicle can be driven as the power transmission path in the
automatic ratio shift portion 20 is connected; that is, at least
one of the first clutch C1 and the second clutch C2 is engaged, as
shown in the engagement operation table of FIG. 2.
[0067] Concretely, when the shift lever 52 is manually operated
from the "P" position or the "N" position to the "R" position, the
second clutch C2 is engaged, so that the power transmission path in
the automatic ratio shift portion 20 is changed from the power
transmission cut-off state to the power transmission-capable state.
When the shift lever 52 is manually operated from the "N" position
to the "D" position, at least the first clutch C1 is engaged, so
that the power transmission path in the automatic ratio shift
portion 20 is changed from the power transmission cut-off state to
the power transmission-capable state. Besides, when the shift lever
52 is manually operated from the "R" position to the "P" position
or the "N" position, the second clutch C2 is released, so that the
power transmission path in the automatic ratio shift portion 20 is
changed from the power transmission-capable state to the power
transmission cut-off state. When the shift lever 52 is manually
shifted from the "D" position to the "N" position, the first clutch
C1 and the second clutch C2 are released, so that the power
transmission path in the automatic ratio shift portion 20 is
changed from the power transmission-capable state to the power
transmission cut-off state.
[0068] FIG. 7 is a functional block diagram illustrating portions
of the control functions performed by the electronic control unit
80. In FIG. 7, a stepped ratio shift control device 82 determines
whether or not to execute a ratio shift of the automatic ratio
shift portion 20, that is, determines the speed change step to
which the automatic ratio shift portion 20 is to be shifted, on the
basis of the state of the vehicle shown by the actual vehicle speed
V and the requested output torque TOUT of the automatic ratio shift
portion 20 in a pre-stored relationship (a shift chart, a shift
map) including an upshift line (solid line) and a downshift line
(dashed one-dotted line) which is represented by using, as
variables, the vehicle speed V and the output torque TOUT of the
automatic ratio shift portion 20 as shown in FIG. 8. Then, the
stepped ratio shift control device 82 executes an automatic ratio
shift control of the automatic ratio shift portion 20 so that the
determined speed change step will be obtained.
[0069] At this time, the stepped ratio shift control device 82
outputs to a hydraulic control circuit 70 a command to engage
and/or release the hydraulic type friction engagement devices
involved in the ratio shift of the automatic ratio shift portion 20
(a ratio shift output command, an oil pressure command), that is, a
command to execute a clutch-to-clutch shift by releasing the
release-side engagement device involved in the ratio shift of the
automatic ratio shift portion 20 and engaging the engagement-side
engagement device involved in the ratio shift of the automatic
ratio shift portion 20. The hydraulic control circuit 70, following
the command, operates the hydraulic actuators of the hydraulic type
friction engagement devices involved in the ratio shift by
operating the corresponding linear solenoid valves SL in the
hydraulic control circuit 70 so that, for example, the release-side
engagement device is released and the engagement-side engagement
device is engaged to carry out the ratio shift of the automatic
ratio shift portion 20.
[0070] FIG. 14 is a time chart showing an example of the process of
engagement of a friction engagement device that is commonly used.
In FIG. 14, the horizontal axis represents time t (sec), and the
vertical axis represents the command value of the engagement
pressure PSL (kPa) that is the oil pressure supplied to the
friction engagement device.
[0071] The stepped ratio shift control device 82 makes a ratio
shift determination, and outputs a command for engagement to a
friction engagement device that is to be engaged. Specifically, at
a time t31, the oil pressure starts to be supplied to the friction
engagement device that is to be engaged according to the determined
ratio shift. Firstly, for the period of the time t31 to a time t32,
such a high engagement pressure that the working oil is rapidly
charged is designated in order to quickly eliminate the back
clearance of the friction engagement device (i.e., a fast-fill
control is execute). Subsequently at the time t32, an engagement
standby pressure PW that is an engagement pressure lower than the
high engagement pressure is designated. The engagement standby
pressure PW is maintained for a predetermined time. The standby
with the engagement standby pressure PW is performed for the
following reason. That is, if the engagement is started with the
high engagement pressure set for the fast-fill control, a shock
occurs. In order to avoid the shock, a lower engagement pressure is
designated at the time point of starting the engagement. After
that, at a time t33, the engagement of the friction engagement
device is started, and the command value of the engagement pressure
PSL is gradually raised. Then, at a time t34 when the command value
of the engagement pressure reaches a predetermined value, an
engagement pressure corresponding to a completely engaged state of
the friction engagement device is designated. In addition, the
period from the time t31 to the time t34 is termed the period of
switching from the non-engaged state to the engaged state.
[0072] At this time, the engagement standby pressure PW is
determined on the basis of, for example, the input torque to the
automatic ratio shift portion 20, that is, the torque of the
transmission member 18. Concretely, the engagement standby pressure
PW is set at a large value within such a magnitude that the
engagement of the friction engagement device is not started.
Therefore, if the input torque to the automatic ratio shift portion
20 is a large value, the engagement standby pressure PW is caused
to be a small value. If the input torque to the automatic ratio
shift portion 20 is a small value, the engagement standby pressure
PW is caused to be a large value.
[0073] The hybrid control device 84 functions as a differential
motion portion control device, and operates the engine 8 in a
high-efficiency operation region, and also controls the speed
change ratio .gamma.0 of the differential motion portion 11 as an
electric continuously variable transmission by changing the
distribution of drive force between the engine 8 and the second
electric motor M2 and the reaction force caused by the power
generation of the first electric motor M1 in an optimum fashion.
For example, given a present traveling vehicle speed V, a target
(requested) output of the vehicle is calculated from the vehicle
speed V and the accelerator operation amount Acc as a driver's
requested output amount. From the target output of the vehicle and
the requested charge value, a necessary total target output is
calculated. Then, taking into account the transmission loss, the
accessory load, the assist torque of the second electric motor M2,
etc., a target engine output is calculated so that the foregoing
total target output will be obtained. Then, the engine 8 is
controlled so as to produce an engine rotation speed NE and an
engine torque TE that achieve the target engine output, and the
amount of electric power generation of the first electric motor M1
is controlled.
[0074] Thus, the overall speed change ratio .gamma.T that is the
speed change ratio of the transmission mechanism 10 as a whole is
determined by the speed change ratio .gamma.0 of the differential
motion portion 11 controlled by the hybrid control device 84 and
the speed change ratio .gamma. of the automatic ratio shift portion
20 controlled by the stepped ratio shift control device 82.
Therefore, the stepped ratio shift control device 82 and the hybrid
control device 84 combined can be regarded as a ratio shift control
device 81. On the basis of the signal PSH representing the shift
position which is output from the shift operation device 50 in
response to the driver's operation of the shift lever 52, the ratio
shift control device 81 changes the overall speed change ratio
.gamma.T of the transmission mechanism 10 within, for example, the
range of shift corresponding to the shift position PSH.
[0075] For example, the hybrid control device 84 executes the
control, by factoring in the speed change step of the automatic
ratio shift portion 20 for the purpose of improving the power
performance, the fuel economy, or the like. In this hybrid control,
the differential motion portion 11 is caused to function as an
electric continuously variable transmission in order to achieve
conformity between the engine rotation speed NE determined in order
to operate the engine 8 in a high-efficiency operation region and
the rotation speed of the transmission member 18 determined by the
vehicle speed V and the speed change step of the automatic ratio
shift portion 20. Specifically, the hybrid control device 84
determines a target value of the total speed change ratio .gamma.T
of the transmission mechanism 10 such that the engine 8 is operated
following a pre-stored optimum specific fuel consumption curve
(fuel economy map) of the engine 8 as shown by an interrupted line
in FIG. 9 which is empirically determined beforehand so that both
good operation characteristic and good fuel economy can be achieved
during the stepless-ratio-shift travel of the vehicle in a
two-dimensional coordinate system constructed of the engine
rotation speed NE and the output torque (engine torque) TE of the
engine 8, for example, such that an engine torque TE and an engine
rotation speed NE for achieving the engine output that is needed in
order to achieve the target output (the total target output, the
requested drive force) will be obtained. Taking into account the
speed change step of the automatic ratio shift portion 20, the
speed change ratio .gamma.0 of the differential motion portion 11
is controlled so that the target value will be obtained. In this
manner, the total speed change ratio .gamma.T is controlled
steplessly within the range of change in which the ratio can be
shifted.
[0076] At this time, the hybrid control device 84 supplies the
electric energy generated by the first electric motor M1 to the
electricity storage device 56 or the second electric motor M2
through an inverter 54. Therefore, while a major portion of the
power of the engine 8 is mechanically transmitted to the
transmission member 18, a portion of the power of the engine 8 is
consumed for the electric power generation by the first electric
motor M1, and is thereby converted into electric energy, which is
supplied to the second electric motor M2 through the inverter 54,
so that the second electric motor M2 is driven and the motive power
output by the second electric motor M2 is transmitted to the
transmission member 18. The devices or the like involved in a
process from the generation of electric energy to the consumption
thereof by the second electric motor M2 form an electric path in
which a portion of the power of the engine 8 is converted into
electric energy and then the electric energy is converted into
mechanical energy.
[0077] In particular, in the case where the ratio shift control of
the automatic ratio shift portion 20 is executed by the stepped
ratio shift control device 82, the total speed change ratio
.gamma.T of the transmission mechanism 10 is changed stepwise
before, when and after the speed change ratio of the automatic
ratio shift portion 20 is changed stepwise. Since the total speed
change ratio .gamma.T changes stepwise, that is, since the speed
change ratio does not continuously change, but jumps, the drive
torque can be changed quickly in comparison with the continuous
changing of the total speed change ratio .gamma.T. However, there
is a possibility of occurrence of a shift shock, or a possibility
of the fuel economy deteriorating as the engine rotation speed NE
cannot be controlled so as to be along an optimum specific fuel
consumption curve.
[0078] Therefore, the hybrid control device 84 executes a ratio
shift of the differential motion portion 11 so that the ratio shift
of the differential motion portion 11 changes in a direction
opposite to the direction of change in the speed change ratio of
the automatic ratio shift portion 20 synchronously with the ratio
shift of the automatic ratio shift portion 20, in such a manner
that the stepwise change of the total speed change ratio .gamma.T
is restrained. In other words, the hybrid control device 84
executes the ratio shift control of the differential motion portion
11 synchronously with the ratio shift control of the automatic
ratio shift portion 20 so that the total speed change ratio
.gamma.T of the transmission mechanism 10 continuously changes
before, when and after the automatic ratio shift portion 20 is
shifted in the transmission ratio. For example, in order to
transitionally form such a predetermined total speed change ratio
.gamma.T of the transmission mechanism 10 that the total speed
change ratio .gamma.T does not change before and after the ratio
shift of the automatic ratio shift portion 20, the hybrid control
device 84, synchronously with the ratio shift control of the
automatic ratio shift portion 20, executes the ratio shift control
of the differential motion portion 11 so that the speed change
ratio is changed stepwise by an amount of change that corresponds
to a stepwise change of the speed change ratio of the automatic
ratio shift portion 20, in a direction opposite to the direction of
change of the speed change ratio of the automatic ratio shift
portion 20.
[0079] From another standpoint, when the ratio shift of the
automatic ratio shift portion 20 is executed so that the speed
change ratio of the automatic ratio shift portion 20 is changed
stepwise, the hybrid control device 84 controls the speed change
ratio .gamma.0 of the differential motion portion 11 so that the
point of operation of the engine 8 does not change before and after
the ratio shift of the automatic ratio shift portion 20. For
example, in FIG. 9, curves P1, P2, P3 are an example of equal power
lines P of the engine 8, and a point A is an example of the point
of operation of the engine 8, that is, the state of drive of the
engine 8, that is defined by the engine rotation speed NE and the
engine torque TE that are set on the basis of the fuel consumption
efficiency (optimum specific fuel consumption) of the engine 8 when
a necessary engine output P2 is produced. Then, the hybrid control
device 84 executes a so-called equal-power ratio shift in which the
differential motion portion 11 is ratio-shifted so that before and
after the ratio shift of the automatic ratio shift portion 20, the
point of operation of the engine 8 as shown by the point A does not
change, or remains on the equal power line, that is, the point of
operation of the engine 8 is along the optimum specific fuel
consumption curve, and the power is kept equal. More concretely,
during the ratio shift of the automatic ratio shift portion 20, the
hybrid control device 84 executes a throttle control so that the
engine torque TE is kept substantially constant, and the hybrid
control device 84 also changes the first electric motor rotation
speed NM1 in a direction opposite to the direction of the change of
the second electric motor rotation speed NM2 associated with the
ratio shift of the automatic ratio shift portion 20 so that the
engine rotation speed NE is kept substantially constant.
[0080] Furthermore, regardless of whether the vehicle is at a stop
or is running, the hybrid control device 84 is able to control the
engine rotation speed NE to a substantially constant speed or
arbitrary speeds by controlling, for example, the first electric
motor rotation speed NM1, through the use of the electric CVT
function of the differential motion portion 11. In other words, the
hybrid control device 84 is able to control the first electric
motor rotation speed NM1 to arbitrary rotation speeds while
controlling the engine rotation speed NE at a substantially
constant speed or arbitrary rotation speeds. For example, as can be
seen from the alignment chart of FIG. 3, when the engine rotation
speed NE is to be raised while the vehicle is running, the hybrid
control device 84 raises the first electric motor rotation speed
NM1 while keeping substantially constant the second electric motor
rotation speed NM2 that is restrained by the vehicle speed V (the
driving wheels 34).
[0081] Furthermore, the hybrid control device 84 controls the
engine output control device 58. That is, the hybrid control device
84 outputs to the engine output control device 58 one of or a
combination of commands to control the opening and closing of the
electronic throttle valve 62 by using the throttle actuator 64 for
the throttle control, and control the amount of fuel injection and
the timing of fuel injection from the fuel injection device 66 for
the fuel injection control, and control the ignition timing of the
ignition device 68, such as an igniter or the like, for the
ignition timing control. The engine output control device 58
executes the output control of the engine 8 so that a necessary
engine output is produced.
[0082] For example, the engine output control device 58, following
a command from the hybrid control device 84, drives the throttle
actuator 64 basically on the basis of the accelerator operation
amount Acc from the pre-stored relationship (not shown), and thus
executes the throttle control so that the throttle valve opening
degree .theta.TH increases as the accelerator operation amount Acc
increases. In addition to executing the control of opening or
closing the electronic throttle valve 62 via the throttle actuator
64 for the throttle control, the engine output control device 58
controls the fuel injection by the fuel injection device 66 for the
fuel injection control, and also controls the ignition timing by
the ignition device 68, such as an igniter or the like, for the
ignition timing control, etc., thereby executing an engine torque
control, in accordance with another command from the hybrid control
device 84.
[0083] Furthermore, the hybrid control device 84 is able to cause a
motor travel of the vehicle by the electric CVT function
(differential motion effect) of the differential motion portion 11,
regardless of whether the engine 8 is at a stop or in an idling
state.
[0084] For example, using a pre-stored relationship (a drive force
source switch diagram, a drive force source map) involving a border
line between the engine travel region and the motor travel region
defined for switching the vehicle-running drive force source
between the engine 8 and the second electric motor M2 which is
represented by using the vehicle speed V and the output torque TOUT
of the automatic ratio shift portion 20 as shown in FIG. 8, the
hybrid control device 84 determines whether the present vehicle
travel region is the motor travel region or the engine travel
region, and accordingly executes the motor travel or the engine
travel of the vehicle, on the basis of the state of the vehicle
that is shown by the actual vehicle speed V and the requested
output torque TOUT of the automatic ratio shift portion 20 in the
relationship. The drive force source shown by a solid line A in
FIG. 8 is pre-stored together with a ratio shift map shown by solid
lines and dashed one-dotted lines in FIG. 8. Thus, the motor travel
caused by the hybrid control device 84 is executed in a relatively
low output torque TOUT region, that is, a low engine torque TE
region, in which the engine efficiency is generally considered low
in comparison with a high torque region, or in a relatively low
vehicle speed region in which the vehicle speed V is relatively
low, that is, a low load region.
[0085] During the motor travel, in order to improve the fuel
economy by restraining the dragging of the stopped engine 8, the
hybrid control device 84 keeps the engine rotation speed NE at zero
or substantially zero, if necessary, due to the electric CVT
function (differential motion effect) of the differential motion
portion 11, by controlling the first electric motor rotation speed
NM1 at a negative rotation speed so that, for example, the first
electric motor M1 is put into a no-load state, and therefore into a
freewheeling state.
[0086] Furthermore, even during the engine travel region, the
hybrid control device 84 is able to perform a so-called torque
assist for supplementing the power of the engine 8 by supplying the
second electric motor M2 with the electric energy from the
electricity storage device 56 and/or the electric energy from the
first electric motor M1 via the aforementioned electric path and
therefore driving the second electric motor M2 to apply torque to
the driving wheels 34.
[0087] Furthermore, the hybrid control device 84 is able to bring
about a state in which the differential motion portion 11 is unable
to transmit torque, that is, a state that is substantially the same
as the state in which the power transmission path within the
differential motion portion 11 is cut off and that is also a state
in which no output is produced from the differential motion portion
11, by putting the first electric motor M1 into the no-load state
so that the first electric motor M1 freely rotates, that is,
freewheels. That is, the hybrid control device 84 is able to put
the differential motion portion 11 into a neutral state in which
the power transmission path of the differential motion portion 11
is electrically cut off, by putting the first electric motor M1
into a non-load state.
[0088] Thus, in the drive force source map as shown in FIG. 8, the
motor travel region is a relatively low torque output torque TOUT
that is generally considered to allow lower engine efficiency than
a high torque region, or a relatively low vehicle speed V region,
that is, the motor travel is executed in a low load region.
Besides, although not shown in FIG. 8, in the case of the "R"
position, that is, where the vehicle is reversed, the vehicle is
run by the motor without the use of the engine, since the vehicle
speed is relatively low when the vehicle is reversed. Therefore,
for example, at the time of a garage shift (N.fwdarw.D shift,
N.fwdarw.R shift or P.fwdarw.R shift) in which the shift lever 52
is operated from the "N" position to the "D" position or the "R"
position at the time of a predetermined low vehicle speed or stop
of the vehicle, the hybrid control device 84 causes the vehicle to
travel by the power from the electric motor not from the
engine.
[0089] Incidentally, during a state in which the state of charge
SOC of a storage battery 56 is low, or in the case where the engine
8 needs a warm-up operation, the hybrid control device 84 starts up
the engine 8 even in the case where it has been determined that the
motor travel should be performed from the drive force source map
represented by the line A in FIG. 8. That is, the engine 8 is
sometimes driven even when the output of the engine 8 is not used
to drive the vehicle.
[0090] In such a case, the hybrid control device 84 controls the
first electric motor M1 so as to generate electric power so that
the rotation speed of the first ring gear R1 (the third rotating
element RE3) rotated by the second electric motor M2 is not
affected, that is, so that the rotation speed does not change, or
controls the first electric motor M1 so that the first electric
motor M1 is put into the no-load state, and therefore freewheels,
so that in the differential motion portion 11, the power
transmission is cut off, and the rotation speed of the first ring
gear R1 (the third rotating element RE3) rotated by the second
electric motor is not affected. However, even in the case where the
first electric motor M1 is controlled in this manner, the rotation
speed of the first ring gear R1 (third rotating element RE3), that
is, the transmission member 18, is not absolutely unaffected, but
is subject to a change. Particularly at the time of a garage shift,
that is, a shift operation performed while the vehicle is traveling
at low vehicle speed or is at a stop, such a change in the rotation
speed can be a factor that causes a shock.
[0091] Therefore, a torque change detection device 86 detects a
change in the input torque to the input shaft of the transmission
mechanism 10, for example, on the basis of a command to start the
engine 8 or a command to stop it from the hybrid control device 84.
The engine start command or the engine stop command, for example,
may be associated with the start or end of the warm-up operation of
the engine 8 as described above, or may also be based on an
electrical charging control of causing the first electric motor M1
to start electric power generation for the purpose of charging the
electricity storage device 56 due to a declined state of charge
thereof or the active charging for warm-up of the electricity
storage device 56, or may also be based on an electrical discharge
control for causing the discharge of the electricity storage device
56 for restraining the excessive SOC thereof or for performing
active discharge for warm-up of the electricity storage device
56.
[0092] In the case where the shift lever 52 is operated in the
manner of the garage shift from the "N" position or the "P"
position that establishes the non-driving state of the vehicle to
the "D" position or the "R" position that establishes the driving
state of the vehicle, the stepped ratio shift control device 82
normally starts the engagement of the friction engagement devices
corresponding to the selected range (e.g., the clutch C1 and the
brake B3 in the case where the shift lever 52 is switched from the
"N" position to the "D" position, and the first speed step is
established), among the friction engagement devices provided in the
automatic ratio shift portion 20, in accordance with, for example,
the time chart shown in FIG. 14, on the assumption that in this
case, a relatively small torque is input to the automatic ratio
shift portion 20. At this time, the value of the engagement standby
pressure PW is determined on the basis of the input torque to the
automatic ratio shift portion 20 as described above. At the time of
the garage shift, since it is normally the case that the
accelerator pedal is not operated or the amount of operation of the
accelerator pedal is very small and therefore the torque generated
by the second electric motor M2 is relatively small, the engagement
standby pressure PW is set at a relatively high pressure. In
addition, in the case where the accelerator operation amount Acc is
0, that is, the accelerator pedal is not depressed, the second
electric motor M2 produces a pseudo-creep torque that corresponds
to the so-called creep torque, and therefore causes a pseudo-creep
state. In this case, therefore, torque is input to the transmission
member 18 even when the accelerator operation amount Acc is
zero.
[0093] By the way, during the switch of the transmission mechanism
10 from the non-driving state to the driving state which is
executed in association with the garage shift operation, the
command values of the engagement pressure of the clutches and the
brakes, which are the friction engagement devices, are output as
shown FIG. 14, as described above. Consequently, during the switch
from the non-engaged state to the engaged state, the actual
engagement pressure is gradually raised, and the friction
engagement device has an engagement capacity corresponding to the
engagement pressure. Then, in the case where the input torque is
within such a range that the engagement capacity is not exceeded,
the friction engagement device assumes the engaged state. On the
other hand, in the case where a torque exceeding the engagement
capacity is input, the friction engagement device has a slip, so
that no more torque transmission is performed. In addition, the
period during which the transmission mechanism 10 is being switched
from the non-driving state to the driving state refers to a period
of time from a time point at which one of the release of the
friction engagement device to be released at the time of the change
of the transmission mechanism 10 from the non-driving state to the
driving state and the engagement of the friction engagement device
to be engaged at the time of the same change of the transmission
mechanism 10 that is to first start to be performed starts to be
performed to a time point at which one of the release of the
friction engagement device to be released at the time of the change
of the transmission mechanism 10 from the non-driving state to the
driving state and the engagement of the friction engagement device
to be engaged at the time of the same change of the transmission
mechanism 10 that is to last finish being performed finishes being
performed.
[0094] In the case where the engine 8 is started up, a change in
input torque occurs in the transmission mechanism 10 and,
particularly, in the automatic ratio shift portion 20. In the case
where such a change in the input torque occurs during the period of
the switch of the friction engagement device from the non-engaged
state to the engaged state, a torque change that is smaller than a
transmission capacity that is set such that a movement of the
vehicle based on a garage shift can be sufficiently performed is
transmitted to the driving wheels via the friction engagement
device, so that a shock occurs on the vehicle.
[0095] Therefore, in the case where a change in the torque input to
the transmission mechanism 10 is detected by the torque change
detection device 86 during the switch of the transmission mechanism
10 from the non-driving state to the driving state which is
executed by the stepped ratio shift control device 82, an
engagement process alteration device 88 alters the engagement
standby pressure of the clutch as shown by the solid line in FIG.
11. That is, in order to reduce the influence that the change in
input torque gives to the shift shock of the vehicle, at least a
portion of the engagement process of the friction engagement
devices that are engaged when the transmission mechanism 10 is
switched from the non-driving state to the driving state (e.g., the
clutch C1 and the brake B3 in the case where the first speed step
of the automatic ratio shift portion 20 is established in the
N.fwdarw.D garage shift), that is, at least a portion of the
process of rise of the engagement torque or engagement oil
pressure, is altered; for example, an ordinary engagement process
as shown in FIG. 14 is altered to an engagement standby pressure as
shown by a solid line in FIG. 11 which is different from the
ordinary engagement process.
[0096] Concretely, for example, in the process of engagement of the
friction engagement devices at the time of the switch of the
transmission mechanism 10 from the non-driving state to the driving
state (e.g., the clutch C1 and the brake B3 in the case where the
first speed step of the automatic ratio shift portion 20 is
established in the N.fwdarw.D garage shift), the engagement process
alteration device 88 alters the value of the engagement standby
pressure PW to a smaller value PW' (PW'<PW). Then, the value of
the engagement standby pressure is kept at PW' until the end of the
change in the input torque, and is returned to the previous value
PW, for example, after the change in the input torque has ceased
being detected by the torque change detection device 86.
Specifically, by changing the value of the engagement standby
pressure to the smaller-than-usual value PW', the engagement
capacity of the friction engagement device is lessened. That is, by
allowing a slip to occur with a lessened input torque, the
influence of the change in the input torque giving a shock to the
vehicle is reduced. At this time, if the post-alteration engagement
standby pressure PW' is an excessively low value, for example, a
minimum value that can be conceived as a command value, a great
time lag occurs when the friction engagement device is engaged.
Therefore, by setting the post-alteration engagement standby
pressure PW' at a value that factors in the occurrence of time lag,
for example, at a value close to the clutch piston stroke end
pressure, the time lag can be reduced.
[0097] Of the cases where a change in the torque input to the
transmission mechanism 10 is detected by the torque change
detection device 86 during the switch of the transmission mechanism
10 from the non-driving state to the driving state executed by the
stepped ratio shift control device 82, there are cases where the
change in the input torque is due to, for example, a driver's
operation on the accelerator, that is, the change in the input
torque is based on the driver's intention to start moving the
vehicle. If in such a case, the engagement process alteration
device 88 alters the value of the engagement standby pressure PW,
the behavior of the vehicle sometimes does not become what properly
reflects the driver's intention. Therefore, the engagement process
alteration device 88 is designed to execute the alteration of the
value of the engagement standby pressure PW only in the cases where
it is determined by a driver's intention determination device 90
(described below) that the driver's intention to start moving the
vehicle is low.
[0098] Besides, in the case where although a change in the torque
input to the transmission mechanism 10 is detected by the torque
change detection device 86 during the switch of the transmission
mechanism 10 from the non-driving state to the driving state
executed by the stepped ratio shift control device 82, the vehicle
speed, for example, detected by a vehicle speed sensor 112 as a
vehicle speed-related value detection device, exceeds a
predetermined value, it cannot be said that the present operation
is based on the garage shift. It is considered that, in that case,
priority should be given to the vehicle start response rather than
to the reduction of a shock. Therefore, the engagement process
alteration device 88 is designed to perform the foregoing function
only in the case where the vehicle is in a stopped state or a very
low vehicle speed state in which the vehicle speed detected by the
vehicle speed sensor 112 is less than or equal to the predetermined
value. In addition, the vehicle speed sensor 112 is, for example, a
rotation sensor that detects the rotation speed of the output shaft
of the vehicle power transmission device. The vehicle speed is
calculated on the basis of the value detected by the rotation
sensor, the gear ratio of the final speed reducer 32, the diameter
of the driving wheels 34, etc.
[0099] The driver's intention determination device 90,
corresponding to a vehicle start intention determination device,
determines whether or not the driver has intended to start the
vehicle, on the basis of whether or not the output of a sensor or
switch provided in the vehicle reflects an operation performed by a
driver to start the vehicle. Concretely, it is determined whether
or not there is a driver's intention to start the vehicle on the
basis of at least one of the accelerator operation amount Acc
detected by an accelerator operation amount sensor 102 which
corresponds to the amount of the driver's depression of an
accelerator pedal 116, the output of a brake switch 104 for
detecting whether a brake pedal 114 is being operated by the
driver, and the output oil pressure of a brake master cylinder 110
detected by a master cylinder pressure sensor 106 which corresponds
to the depression force on the brake pedal and the amount of
depression (stroke) thereof each of which is the amount of braking
operation that represents the driver's intention to brake and the
degree of the braking. More concretely, it is determined that the
driver has an intention to start the vehicle, if at least a
predetermined one of the following conditions is satisfied: a
condition that the accelerator operation amount Acc be greater than
a predetermined value; a condition that the brake pedal 114 be not
being operated; and a condition that the brake master cylinder
pressure be below a predetermined value.
[0100] FIG. 10 is a flowchart generally showing the operation of a
control device of the vehicle power transmission device of the
invention. Firstly in step SA1 (hereinafter, the "step" will be
omitted) corresponding to the stepped ratio shift control device
82, it is determined whether or not the automatic ratio shift
portion 20 is presently being switched from the non-driving state
to the driving state, that is, whether or not the friction
engagement device to be engaged during the switch of the automatic
ratio shift portion 20 from the non-driving state to the driving
state is presently being switched from the non-engaged state to the
engaged state, when a determination about a ratio shift including
the switch of the automatic ratio shift portion 20 from the
non-driving state to the driving state has been made. Concretely,
for example, in the case where the change from the N range to the D
range is performed by the shift operation device 50 and the
automatic ratio shift portion 20 is set at the first speed step
from the N (neutral) state, the foregoing determination in SA1 is
made on the basis of whether at least one of the clutch C1 and the
brake B3 is being switched. This determination is performed on the
basis of, for example, a prescribed time chart of a switch shown in
FIG. 14, and the elapsed time after the shift determination has
been made. Then, if an affirmative determination is made in this
state, that is, if it is determined that the friction engagement
device is being switched from the non-engaged state to the engaged
state, the process from SA2 on is executed. On the other hand, if a
negative determination is made in this step, for example, if all
the friction engagement devices have been switched to the engaged
state, controls other than the foregoing control, that is, the
control of altering the engagement processes of the friction
engagement device, are executed in SA8 in accordance with needs.
Then, the flowchart ends.
[0101] In SA2, corresponding to the torque change detection device
86, it is determined whether or not a control for starting up the
engine 8 (hereinafter, referred to as "the start-up control") is
being performed, on the basis of, for example, whether or not it is
determined by the hybrid control device 84 that the electricity
storage device 56 needs to be charged due to a decline in the SOC,
or whether or not it is determined that the warm-up operation of
the engine 8 is needed due to a decline in the engine cooling water
temperature. If an affirmative determination is made in this step,
that is, if it is determined that the start-up control of the
engine is being executed, the process of SA3 is executed. On the
other hand, if a negative determination is made in this step, that
is, if it is determined that the start-up control of the engine is
not being executed, the engagement process of the friction
engagement device is not altered. Then in SA7, the engagement of
the friction engagement device is executed by an ordinary
engagement process of the friction engagement device, that is, a
prescribed engagement process, such as an engagement process shown
in FIG. 14.
[0102] SA3 and SA4, which follow SA2, correspond to the driver's
intention determination device 90. In SA3, it is determined whether
or not the value of the accelerator operation amount Acc detected
by the accelerator operation amount sensor 102 is less than or
equal to a predetermined value. Subsequently in SA4, it is
determined whether or not a predetermined brake operating has been
performed. The determination that the predetermined brake operation
has been performed herein means, for example, satisfaction of one
of the condition that an operation of the brake pedal 114 detected
by the brake switch 104 be performed, and the condition that the
output oil pressure of the brake master cylinder 110 detected by
the master cylinder pressure sensor 106 be greater than or equal to
a predetermined value. Furthermore, in SA5, it is determined
whether or not the vehicle speed detected by the vehicle speed
sensor 112 that corresponds to the vehicle speed-related value
detection device is less than or equal to a predetermined value. If
an affirmative determination is made in each of the three steps,
that is, SA3 to SA5, the process of SA6 is subsequently executed.
On the other hand, if a negative determination is made in any one
of the three steps, that is, SA3 to SA5, the alteration of the
engagement process of the friction engagement device is not
performed; instead, in SA7, the engagement of the friction
engagement device is executed by an ordinary engagement process of
the friction engagement device, that is, a prescribed engagement
process, such as the engagement process shown in FIG. 14.
[0103] In SA6, corresponding to the engagement process alteration
device 88, the process of engagement of the friction engagement
devices to be engaged during the switch of the transmission
mechanism 10 from the non-driving state to the driving state (e.g.,
the clutch C1 and the brake B3 in the case where the automatic
ratio shift portion 20 is set at the first speed step in the
N.fwdarw.D garage shift) is altered. Concretely, for example, the
value of the engagement standby pressure PW in the engagement of
the friction engagement devices is altered to a smaller value PW'
(PW'<PW). Then, the value of the engagement standby pressure is
kept at PW', for example, until the start-up control of the engine
8 ends.
[0104] FIG. 11 is an example of a time chart for describing the
control operation of a control device of the vehicle power
transmission device of the invention. FIG. 11 shows the operation
of the shift operation device 50, the command value of the
engagement pressure of the friction engagement device that is
engaged by a shift operation, the output torque of the first
electric motor M1, the output torque of the second electric motor
M2, and the presence/absence of the start-up control of the engine
along the vertical axis, together with time along the horizontal
axes of the same scale.
[0105] At a time t1, a start-up control for starting up the engine
8, which has been caused to be at rest by the hybrid control device
84, is started on the basis of, for example, a decline of the SCO
of the electricity storage device 56. Due to the start of the
start-up control, the output torques of the first electric motor M1
and the second electric motor M2 are raised. The torque of the
first electric motor M1 is raised in order to operate the first
electric motor M1 as a starter motor of the engine 8 so as to cause
the engine 8 to rotate at a rotation speed that allows the
self-sustaining operation thereof, for example, about 600 rpm. The
torque of the second electric motor M2 is raised in order to
prevent the second electric motor M2 from being rotated by the
rising torque of the first electric motor M1 and therefore prevent
the engine 8 from freewheeling or rotating in a similar manner
without a load.
[0106] Then, at a time t2 in an interval during which the start-up
control is executed, the shift operation device 50 is operated by
the driver so that the shift from the N range to the D range is
executed. This shift is a shift in which the transmission mechanism
10, that is, the vehicle power transmission device, is switched
from the non-driving state to the driving state. Since at this
time, the start-up control of the engine is being executed, that
is, since the engine 8 is to be started up later during the switch
of the transmission mechanism 10, a change in the input torque to
the transmission mechanism 10 is about to occur. Therefore, the
change in the input torque is detected by the torque change
detection device 86.
[0107] In accordance with the foregoing shift operation, the
stepped ratio shift control device 82 supplies engagement pressure
to the friction engagement device or devices that are to be engaged
in the shift operation (e.g., the clutch C1 and the brake B3 in the
case where the first speed step is established due to the shift
from the N range to the D range). At this time, in the case where
it is determined by the driver's intention determination device 90
that the degree of the driver's intention to start the vehicle is
low or where the vehicle speed detected by the vehicle speed sensor
112 is lower than a predetermined value, the clutch transmission
capacity during the switching of the state is switched by the
engagement process alteration device 88 to a value that is
different from the value used on an ordinary occasion, that is, in
the case where the change in the torque is not detected by the
torque change detection device 86.
[0108] For the period of the time t2 to a time t3, such a high
engagement pressure that the working oil is rapidly charged is
designated in order to quickly eliminate the back clearance of the
friction engagement devices, as in the ordinary operation, as
described above. Subsequently at the time t3, the engagement
standby pressure PW' is designated as an engagement pressure. This
engagement standby pressure PW' is set by the engagement process
alteration device 88 at a value that is smaller than the engagement
standby pressure PW used at the ordinary time. Incidentally, in
FIG. 11, an interrupted line extending from the time t3 to the time
t4 in the diagram showing time-dependent changes in the command
value of the clutch engagement pressure represents ordinary-time
engagement standby pressures PW.
[0109] As for the first electric motor M1 and the second electric
motor M2, the output torques thereof are gradually raised from the
time t1 on, and are brought to the highest value around the time
t2. After the engine 8 reaches the rotation speed that allows the
self-sustaining operation thereof, the output torque of each of the
electric motors M1, M2 is lowered to a predetermined output torque
that is needed in order to maintain the self-sustaining speed of
the engine 8. Then, at a time tEG, the ignition is performed by the
ignition device 68, so that the engine 8 is started up. After the
engine 8 has been started up, the start-up control is ended at a
time t4, and then the output torques of the first electric motor M1
and the second electric motor M2 are brought back to the values set
prior to the start of the start-up control.
[0110] At the time t4, in accordance with the end of the start-up
control, the alteration of the engagement standby pressure by the
engagement process alteration device 88 also ends. Specifically,
the engagement standby pressure that has been set at the
lower-than-ordinary value PW' is set at the ordinary value PW.
Then, at a time t5 at which a predetermined standby time elapses
following the time t3, the command value of the engagement pressure
begins to be gradually raised until a time t6, thus engaging the
friction engagement devices.
[0111] According to the first embodiment, if a change in the input
torque to the transmission mechanism 10 constituting a portion of
the vehicle power transmission device is detected by the torque
change detection device 86 (SA2) while the state of the
transmission mechanism 10 is being switched from a non-driving
state, for example, the neutral state, to a driving state, for
example, the first speed step, by the stepped ratio shift control
device 82 (SA1), the engagement standby pressure PW of the clutches
and the brakes that are the engagement elements of the automatic
ratio shift portion 20 is altered to PW' by the engagement process
alteration device 88 (SA6), so that the transmission capacity of
the engagement elements is switched to a value different from the
value used at the ordinary time, that is, when there does not occur
a change in the input torque to the transmission mechanism 10.
Therefore, the transmission capacity of the engagement element or
elements in a transitional state of engagement of the engagement
elements is changed according to changes in the input torque.
Hence, the shift shock can be reduced even in the case where the
input torque to the transmission mechanism 10 changes during the
switch of the state of the transmission mechanism 10 from the
non-driving state to the driving state.
[0112] Besides, according to the first embodiment, since the change
in the input torque is due to the start-up of the engine 8, the
shift shock caused by the change in the input torque caused by the
start-up of the engine 8 can be reduced.
[0113] Besides, according to the first embodiment, since the change
in the input torque is also due to the stop of the engine 8, the
shift shock caused by the change in the input torque caused by the
stop of the engine 8 can be reduced.
[0114] Besides, according to the first embodiment, since the change
in the input torque is due to the electrical charging control, the
shift shock caused by the change in the input torque owing to the
electrical charging control can be reduced.
[0115] Besides, according to the first embodiment, since the change
in the input torque is due to the electrical discharging control,
the shift shock caused by the change in the input torque owing to
the electrical discharging control can be reduced.
[0116] Besides, according to the first embodiment, the electronic
control unit 80 as the control device of the transmission mechanism
10 includes the vehicle start intention determination device 90
(SA3 to SA4) that determines the degree of the driver's intention
to start the vehicle. If a change in the input torque to the
transmission mechanism 10 is detected by the torque change
detection device 86 (SA2) during the switch of the state of the
transmission mechanism 10 from the non-driving state to the driving
state performed by the stepped ratio shift control device 82 (SA1)
in the case where the degree of the driver's intention to start the
vehicle determined by the vehicle start intention determination
device 90 is low, the engagement standby pressure PW of the
clutches and the brakes that are the engagement elements of the
automatic ratio shift portion 20 is altered to the value PW'
different from the value used till that moment, so that the
transmission capacity of the engagement elements is switched so as
to be different from the ordinary-time transmission capacity. On
the other hand, in the case where the degree of the driver's
intention to start the vehicle is high, the transmission capacity
of the engagement elements is set at the ordinary-time value.
Therefore, a control of the transmission mechanism 10 with a high
regard to response can be performed.
[0117] Besides, according to the first embodiment, the electronic
control unit 80 as the control device of the transmission mechanism
10 includes the vehicle speed sensor 112 (SA5) as a vehicle
speed-related value detection device that detects a vehicle
speed-related value regarding the vehicle speed of the vehicle. If
a change in the input torque to the vehicle power transmission
device is detected by the torque change detection device 86 (SA2)
during the switch of the state of the vehicle power transmission
device from the non-driving state to the driving state performed by
the stepped ratio shift control device 82 (SA1) in the case where
the vehicle speed-related value detected by the vehicle speed
sensor 112 is less than or equal to a predetermined value, the
engagement standby pressure PW of the clutches and the brakes that
are the engagement elements of the automatic ratio shift portion 20
is altered to the value PW' different from the value used till that
moment, so that the transmission capacity of the engagement
elements is switched so as to be different from the ordinary-time
transmission capacity. On the other hand, in the case where the
vehicle speed is higher than the predetermined value, the
transmission capacity of the engagement elements is set at the
ordinary-time value. Therefore, a control of the transmission
mechanism 10 with a high regard to response can be performed.
[0118] Besides, according to the first embodiment, the differential
motion portion 11 as the electrical differential motion portion
operates as a continuously variable transmission when the operation
state of the electric motor is controlled. Therefore, the
transmission mechanism 10 including the differential motion portion
11 and the automatic ratio shift portion 20 can be operated as a
continuously variable transmission, so that the speed change ratio
.gamma.T of the transmission mechanism 10 as a whole can be
smoothly changed. Incidentally, the differential motion portion 11
can also be operated as a stepped ratio transmission by changing
the speed change ratio stepwise, in addition to being operated as
an electric continuously variable transmission by continuously
changing the speed change ratio .gamma.T.
[0119] Besides, according to the first embodiment, the automatic
ratio shift portion 20 as the ratio shift portion is a stepped
ratio transmission. Therefore, in the case where the differential
motion portion 11 is caused to function as an electric continuously
variable transmission, the continuously variable transmission is
constructed of the differential motion portion 11 and the
stepped-type hydraulic-type automatic ratio shift portion 20, so
that the drive torque can be smoothly changed. Furthermore, during
the state in which the differential motion portion 11 is controlled
so that the speed change ratio thereof is constant, a state
substantially equivalent to a stepped ratio transmission is
constructed of the differential motion portion 11 and the
stepped-type hydraulic-type automatic ratio shift portion 20, so
that the overall speed change ratio .gamma.T of the hybrid vehicle
driving device is changed stepwise, and a drive torque can be
promptly obtained.
[0120] Next, a second embodiment of the invention will be
described. In the following description, portions common between
the first and second embodiments are assigned with the same
reference characters, and descriptions thereof are omitted
below.
[0121] In the first embodiment, if a change in the input torque is
detected by the torque change detection device 86 when the vehicle
power transmission device is switched from the non-driving state to
the driving state, the engagement process alteration device 88 sets
the engagement standby pressure of the friction engagement device
or devices that are engaged during the switch of the vehicle power
transmission device, to a value that is lower than the
ordinary-time engagement standby pressure. In the second
embodiment, if a change in the input torque is detected by the
torque change detection device 86 when the vehicle power
transmission device is switched from the non-driving state to the
driving state, the timing at which the friction engagement device
to be engaged by the switching of the vehicle power transmission
device is engaged is delayed from the ordinary timing.
[0122] Incidentally, the second embodiment is also applied to a
vehicle power transmission device that is similar to the device to
which the first embodiment is applied. That is, FIGS. 1 to 10 show
the second embodiment as well, and the descriptions thereof are
omitted below.
[0123] The second embodiment is different from the first embodiment
in the operation of the engagement process alteration device 88
shown in the functional block diagram of FIG. 7. Specifically, if a
change in the torque input to the transmission mechanism 10 is
detected by the torque change detection device 86 during the switch
of the transmission mechanism 10 from the non-driving state to the
driving state executed by the stepped ratio shift control device
82, the engagement process alteration device 88 alters the process
of the switching of the transmission mechanism 10 from the
non-driving state to the driving state, concretely, the process of
the engagement of the friction engagement device or devices, to a
process different from the ordinary process, for example, as shown
in FIG. 14. The content of the alteration is different between the
first and second embodiments.
[0124] Concretely, the engagement process alteration device 88
delays the execution of the switch of the transmission mechanism 10
from the non-driving state to the driving state, that is, the
engagement of the friction engagement device or devices (e.g., the
clutch C1 and the brake B3 in the case where the first speed step
in the automatic ratio shift portion 20 is established in the
N.fwdarw.D garage shift), from the ordinary timing of the
execution. Specifically, in the example shown in FIG. 14, the
driver's operation of the shift operation device 50 and the start
of the engagement of the friction engagement device occur
substantially simultaneously at the time t31. However, according to
the engagement process alteration device 88 of the second
embodiment, the engagement of the friction engagement device is
started after a predetermined time elapses following the driver's
operation of the shift operation device 50. The predetermined time
herein is, for example, in the case where the engine 8 is started
up, a time that is needed before the influence of the start-up of
the engine 8 on the changing of the input torque to the
transmission mechanism 10 decreases to such a degree that the
switch of the transmission mechanism 10 from the non-driving state
to the driving state will not give a shock to the vehicle, and is
calculated empirically or through simulation beforehand.
[0125] In addition, in the second embodiment, similarly to the
first embodiment, the engagement process alteration device 88 is
designed to execute its function only in the case where it is
determined by a driver's intention determination device 90
(described below) that the driver's intention to start the vehicle
is low. Besides, it is also designed so that the function is
executed only in the case where the vehicle speed detected by the
vehicle speed sensor 112 is less than or equal to the predetermined
value.
[0126] The flowchart in FIG. 12 generally shows the operation of a
control device of a vehicle power transmission device in the second
embodiment, and corresponds to the flowchart shown in FIG. 10.
Steps SB1 to SB5 and SB8 (hereinafter, "step" will be omitted) in
FIG. 12 correspond to SA1 to SA5 and SB8 in FIG. 10, and have the
same contents of operation as those steps in FIG. 10; therefore,
the descriptions of the steps are omitted below.
[0127] In SB6, corresponding to the engagement process alteration
device 88, the process of engagement of the friction engagement
device or devices to be engaged at the time of the switch of the
transmission mechanism 10 from the non-driving state to the driving
state (e.g., the clutch C1 and the brake B3 in the case where the
first speed step in the automatic ratio shift portion 20 is
established in the N.fwdarw.D garage shift) is altered. Concretely,
for example, the engagement of the friction engagement devices is
executed with a delay from the ordinary timing of the
engagement.
[0128] On another hand, SB7 is a step that is executed in the case
where a negative determination is made in SB2, that is, it is
determined that the start-up control of the engine is not being
executed, or in the case where a negative determination is made in
any one of three steps SB3 to SB5. In SB7, the alteration of the
engagement process of the friction engagement devices is not
performed, but the engagement of the friction engagement devices is
executed by, for example, following the prescribed engagement
process of the friction engagement devices as shown in FIG. 14.
[0129] FIG. 13 is an example of a time chart for describing the
control operation of the control device of the vehicle power
transmission device in accordance with the second embodiment of the
invention, and corresponds to FIG. 11. FIG. 13 shows the operation
of the shift operation device 50, the command value of the
engagement pressure of the friction engagement device that is
engaged by a shift operation, the output torque of the first
electric motor M1, the output torque of the second electric motor
M2, and the presence/absence of the start-up control of the engine
along the vertical axis, together with time along the horizontal
axes of the same scale.
[0130] At a time t11, a start-up control for starting up the engine
8, which has been caused to be at rest by the hybrid control device
84, is started on the basis of, for example, a decline of the SCO
of the electricity storage device 56. Due to the start of the
engine start-up control, the output torques of the first electric
motor M1 and the second electric motor M2 are raised. The torque of
the first electric motor M1 is raised in order to operate the first
electric motor M1 as a starter motor of the engine 8 so as to cause
the engine 8 to rotate at a rotation speed that allows the
self-sustaining operation thereof. The torque of the second
electric motor M2 is raised in order to prevent the second electric
motor M2 from being rotated by the rising torque of the first
electric motor M1 and therefore prevent the engine 8 from
freewheeling or rotating in a similar manner.
[0131] Then, at a time t12 at which the start-up control is being
executed, the shift operation device 50 is operated by the driver
so that the shift from the N range to the D range is executed. This
shift is a shift in which the transmission mechanism 10, that is,
the vehicle power transmission device, is switched from the
non-driving state to the driving state. Since at this time, the
start-up control of the engine is being executed, it is considered
that as the engine 8 is started up later, that is, during the
switch of the transmission mechanism 10, a change in the input
torque to the transmission mechanism 10 can occur. Therefore, the
change in the input torque is detected by the torque change
detection device 86.
[0132] In accordance with the foregoing shift operation, the
stepped ratio shift control device 82 commands the supply of the
engagement pressure to the friction engagement device or devices
that are to be engaged in the shift operation (e.g., the clutch C1
and the brake B3 in the case where the first speed step is
established due to the shift from the N range to the D range).
However, at this time, in the case where it is determined by the
driver's intention determination device 90 that the degree of the
driver's intention to start the vehicle is low or where the vehicle
speed detected by the vehicle speed sensor 112 is lower than a
predetermined value, the engagement of the friction engagements,
that is, the command to output the engagement pressure, is delayed
in comparison with an ordinary time, that is, when the change in
the torque is not detected by the torque change detection device
86.
[0133] That is, in the case where the delay of the engagement of
the friction engagement devices by the engagement process
alteration device 88 is not performed, such a high engagement
pressure that the working oil is rapidly charged is designated in
order to quickly eliminate the back clearance of the friction
engagement devices, for the period of the time t12 to a time t13,
as in the ordinary operation, as described above. Subsequently,
during a period from the time t13 to a time t15, the engagement
standby pressure PW is designated as an engagement pressure. Then,
during a period from the time t15 to a time t16, the engagement is
executed. Incidentally, in FIG. 13, an interrupted line extending
from the time t12 in the diagram showing time-dependent changes in
the command value of the clutch engagement pressure represents
time-dependent changes of the command value of the ordinary-time
engagement pressure.
[0134] As for the first electric motor M1 and the second electric
motor M2, the output torques thereof are gradually raised from the
time t11 on, and are brought to the highest value around the time
t12. After the engine 8 reaches the rotation speed that allows the
self-sustaining operation thereof, the output torque of each of the
electric motors M1, M2 is lowered to a predetermined output torque
that is needed in order to maintain the self-sustaining speed of
the engine 8. Then, at a time tEG, the ignition is performed by the
ignition device 68, so that the engine 8 is started up. After the
engine 8 has been started up, the start-up control is ended at a
time t14, and then the output torques of the first electric motor
M1 and the second electric motor M2 are brought back to the values
set prior to the start of the start-up control.
[0135] Therefore, the engagement process alteration device 88 does
not give a command to output the engagement pressure to the
friction engagement devices, while a change in the torque is being
detected by the torque change detection device 86, that is, until
the start-up control ends at the time t14. Then, after the start-up
control ends at the time t14 and the detection of a change in the
torque by the torque change detection device 86 ceases, the supply
of the engagement pressure is started. Concretely, such a high
engagement pressure that the working oil is rapidly charged is
designated in order to quickly eliminate the back clearance of the
friction engagement devices, for the period from a time t12' (time
t14) corresponding to the time t12 in the ordinary occasion to a
time t13'. Subsequently, during a period from the time t13' to a
time t15', the engagement standby pressure PW is designated as an
engagement pressure. Then, during a period from the time t15' to a
time t16', the engagement is executed. The amounts of time of rapid
charge before and after the alteration of the engagement process,
that is, before and after the delay of the engagement of the
friction engagement devices (i.e., the pre-alteration interval of
the time t12 to the time t13, and the post-alteration interval of
the time t12' to the time t13'), the amounts of time of standby at
the engagement standby pressure before and after the alteration of
the engagement process (i.e., the pre-alteration interval of the
time t13 to the time t15, and the post-alteration interval of the
time t13' to the time t15'), and the amounts of time of execution
of the engagement before and after the alteration of the engagement
process (i.e., the pre-alteration interval of the time t5 to the
time t6, and the post-alteration interval of the time t15' to the
time t16') are, for example, set as the same amount of time.
[0136] According to the second embodiment, if a change in the input
torque to the transmission mechanism 10 constituting a portion of
the vehicle power transmission device is detected by the torque
change detection device 86 (SB2) while the state of the
transmission mechanism 10 is being switched from a non-driving
state, for example, the neutral state, to a driving state, for
example, the first speed step, by the stepped ratio shift control
device 82 (SB1), the engagement of the clutches and the brakes that
are the engagement elements of the automatic ratio shift portion 20
is delayed by the engagement process alteration device 88 (SB6) in
comparison with at the ordinary time, that is, in comparison with
when there does not occur a change in the input torque to the
transmission mechanism 10. Therefore, the engagement elements are
engaged after the change in the input torque has converged or has
become diminished. Hence, the shift shock can be reduced even in
the case where the input torque to the transmission mechanism 10
changes during the switch of the state of the transmission
mechanism 10 from the non-driving state to the driving state.
[0137] Besides, according to the second embodiment, since the
change in the input torque is due to the start-up of the engine 8,
the shift shock caused by the change in the input torque caused by
the start-up of the engine 8 can be reduced.
[0138] Besides, according to the second embodiment, since the
change in the input torque is also due to the stop of the engine 8,
the shift shock caused by the change in the input torque caused by
the stop of the engine 8 can be reduced.
[0139] Besides, according to the second embodiment, since the
change in the input torque is due to the electrical charging
control, the shift shock caused by the change in the input torque
owing to the electrical charging control can be reduced.
[0140] Besides, according to the second embodiment, since the
change in the input torque is due to the electrical discharging
control, the shift shock caused by the change in the input torque
owing to the electrical discharging control can be reduced.
[0141] Besides, according to the second embodiment, the electronic
control unit 80 as the control device of the transmission mechanism
10 includes the vehicle start intention determination device 90
(SB3 to SB4) that determines the degree of the driver's intention
to start the vehicle. If a change in the input torque to the
transmission mechanism 10 is detected by the torque change
detection device 86 (SA2) during the switch of the state of the
transmission mechanism 10 from the non-driving state to the driving
state performed by the stepped ratio shift control device 82 (SB1)
in the case where the degree of the driver's intention to start the
vehicle determined by the vehicle start intention determination
device 90 is low, the engagement of the engagement elements of the
automatic ratio shift portion 20 is delayed in comparison with at
the ordinary time. On the other hand, in the case where the degree
of the driver's intention to start the vehicle is high, the
engagement of the engagement elements performed as the
ordinary-time engagement. Therefore, a control of the transmission
mechanism 10 with a high regard to response can be performed.
[0142] Besides, according to the second embodiment, the electronic
control unit 80 as the control device of the transmission mechanism
10 includes the vehicle speed sensor 112 (SB5) as a vehicle
speed-related value detection device that detects a vehicle
speed-related value regarding the vehicle speed of the vehicle. If
a change in the input torque to the vehicle power transmission
device is detected by the torque change detection device 86 (SB2)
during the switch of the state of the vehicle power transmission
device from the non-driving state to the driving state performed by
the stepped ratio shift control device 82 (SB1) in the case where
the vehicle speed-related value detected by the vehicle speed
sensor 112 is less than or equal to a predetermined value, the
engagement of the engagement elements of the automatic ratio shift
portion 20 is delayed in comparison with at the ordinary time. On
the other hand, in the case where the vehicle speed, that is, a
vehicle speed-related value, is higher than the predetermined
value, the engagement of the engagement elements is performed as
the ordinary-time engagement. Therefore, a control of the
transmission mechanism 10 with a high regard to response can be
performed.
[0143] Besides, according to the second embodiment, the
differential motion portion 11 as the electrical differential
motion portion operates as a continuously variable transmission
when the operation state of the electric motor is controlled.
Therefore, the transmission mechanism 10 including the differential
motion portion 11 and the automatic ratio shift portion 20 can be
operated as a continuously variable transmission, so that the speed
change ratio .gamma.T of the transmission mechanism 10 as a whole
can be smoothly changed. Incidentally, the differential motion
portion 11 can also be operated as a stepped ratio transmission by
changing the speed change ratio stepwise, in addition to being
operated as an electric continuously variable transmission by
continuously changing the speed change ratio .gamma.T.
[0144] Besides, according to the second embodiment, the automatic
ratio shift portion 20 as the ratio shift portion is a stepped
ratio transmission. Therefore, in the case where the differential
motion portion 11 is caused to function as an electric continuously
variable transmission, the continuously variable transmission is
constructed of the differential motion portion 11 and the
stepped-type hydraulic-type automatic ratio shift portion 20, so
that the drive torque can be smoothly changed. Furthermore, during
the state in which the differential motion portion 11 is controlled
so that the speed change ratio thereof is constant, a state
substantially equivalent to a stepped ratio transmission is
constructed of the differential motion portion 11 and the
stepped-type hydraulic-type automatic ratio shift portion 20, so
that the overall speed change ratio .gamma.T of the hybrid vehicle
driving device is changed stepwise, and a drive torque can be
promptly obtained.
[0145] While the embodiments of the invention have been described
in detail with reference to the drawings, the invention is also
applicable in other forms.
[0146] For example, although the first embodiment and the second
embodiment are described above as separate embodiments, the two
embodiments may also be simultaneously applied to a device.
Specifically, at the time of engagement of the engagement elements,
the engagement process alteration device 88 may delay the output of
the engagement oil pressure in comparison with at the ordinary time
and may also alter the engagement standby pressure PW so that the
engagement standby pressure PW becomes lower than the ordinary-time
value thereof. This will reduce the shift shock and execute the
engagement of the engagement elements earlier than in the case of
only the delay of the output of the engagement oil pressure in
comparison with at the ordinary time.
[0147] Besides, although in the foregoing embodiments, the
alteration of the engagement process of the engagement elements by
the engagement process alteration device 88 (SA6 or SB6) is
executed only in the case where it is determined by the driver's
intention determination device 90 (SA3 and SA4, or SB3 and SB4)
that the driver's intention to start the vehicle is low on the
basis of the accelerator operation amount Acc and one of the master
cylinder pressure and the output of the brake switch, this is not
restrictive. For example, the alteration of the engagement process
of the engagement elements may be executed in the case where it is
determined that the driver's intention to start the vehicle is low
on the basis of at least one of the aforementioned factors.
[0148] Besides, although in the foregoing embodiments, the
alteration of the engagement process of the engagement elements by
the engagement process alteration device 88 is executed only in the
case where it is determined by the driver's intention determination
device 90 that the driver's intention to start the vehicle is low
or where the vehicle speed detected by the vehicle speed sensor 112
is less than or equal to a predetermined speed, this is not
restrictive. The alteration of the engagement process of the
engagement elements by the engagement process alteration device 88
may also be executed simply if a change in the input torque to the
vehicle power transmission device is detected by the torque change
detection device 86 in the case where the automatic ratio shift
portion 20 is controlled so as to change from the non-driving state
to the driving state by the stepped ratio shift control device 82.
In this case, it is not altogether necessary to provide the vehicle
speed sensor 112 and the driver's intention determination device
90.
[0149] Besides, although in the foregoing embodiments, the torque
change detection device 86 detects a change in the input torque to
the transmission mechanism 10 as the vehicle power transmission
device on the basis of the presence/absence of the start-up control
of the engine 8 executed by the hybrid control device 84, this is
not restrictive. For example, it can also be determined whether or
not there is a change in the input torque on the basis of the
presence/absence of the stop control of the engine 8. Besides, a
change in the input torque may also be detected on the basis of
execution of a control that includes the start-up or stop of the
engine 8 as a part of the control, for example, the electrical
charging control, the electrical discharging control, etc. Besides,
the detection of a torque change by the torque change detection
device 86 may be performed by predicting a torque change that is to
occur, or may also be performed on the basis of whether or not the
influence of the torque change that has occurred has converged or
has become diminished.
[0150] Besides, although in the foregoing embodiments, the
engagement process alteration device 88 ends the alteration of the
engagement process of the engagement elements on the basis of the
end of the start-up control of the engine 8, this is not
restrictive. For example, the convergence or diminishment of the
actual change in the input torque to the transmission mechanism 10
may be detected, and the alteration of the engagement process of
the engagement elements may be ended on the basis of the detected
convergence or diminishment of the change in the input torque.
[0151] Besides, although in the foregoing embodiments, the
definition of the period of the switch from the non-driving state
to the driving state is, for example, the period of t31 to t34 in
FIG. 14, this is not restrictive, and other definition may also be
adopted.
[0152] Besides, although in the foregoing embodiments, the vehicle
speed calculated from the value detected by the vehicle speed
sensor 112 provided at the output shaft of the transmission
mechanism 10 is used as the vehicle speed-related value, the
calculation method for the vehicle speed is not limited so. The
vehicle speed may also be calculated on the basis of a detected
rotation speed of the transmission member 18 or a detected rotation
speed of the driving wheels 34. Besides, the vehicle speed-related
value is not limited to the vehicle speed, but may also be an index
that is in a one-to-one relation with the vehicle speed.
[0153] Besides, although in the foregoing embodiments, the driver's
intention determination device 90 determines the driver's intention
to start the vehicle on the basis of the accelerator operation
amount Acc detected by the accelerator operation amount sensor 102,
this is not restrictive. For example, the driver's intention to
start the vehicle may also be determined on the basis of the degree
of throttle opening or the like.
[0154] Besides, although in the foregoing embodiments, the
engagement elements provided in the automatic ratio shift portion
20 are the clutches and the brakes as hydraulic type friction
engagement devices, this is not restrictive. For example,
engagement elements such as a powder clutch, an electromagnetic
clutch, etc., may also be used.
[0155] Besides, although in the foregoing embodiments, the torque
change detection device 86 detects a change in the input torque to
the input shaft of the transmission mechanism 10, for example, on
the basis of the command output by the hybrid control device 84 to
start the engine 8 or to stop the engine, this is not restrictive.
Specifically, the change in the input torque to the transmission
mechanism 10 may be actually detected, and the torque change may be
considered to be detected when a change that is greater than or
equal to a predetermined value is detected.
[0156] Besides, although in the foregoing embodiments, the
engagement process alteration device 88 alters the engagement
standby pressure of the friction engagement device C1 that is a
power connection-disconnection device to a smaller value PW'
(PW'<PW) if a change in the torque input to the transmission
mechanism 10 is detected by the torque change detection device 86
during the switch of the transmission mechanism 10 from the
non-driving state to the driving state executed by the stepped
ratio shift control device 82, the value of PW' is not limited to a
constant value. For example, the value of PW' may be varied
according to the magnitude of the change in the torque detected by
the torque change detection device 86. Concretely, for example, the
value of PW' may be made smaller the larger the detected change in
the torque. Similarly, the time of delay of the engagement of the
friction engagement device C1 as a power connection-disconnection
device that is subjected to the alteration performed by the
engagement process alteration device 88 may also be altered
according to the detected change in the torque.
[0157] Besides, although in the foregoing embodiments, the
differential motion portion 11 is designed so as to operate as a
continuously variable transmission, this is not restrictive. The
differential motion portion 11 may also be operated as a stepped
ratio transmission that achieves one or more of a plurality of
fixed speed change ratios.
[0158] Besides, although in the foregoing embodiments, the
transmission mechanism 10 as a power transmission device has a
construction in which the differential motion portion 11 and the
automatic ratio shift portion 20 are connected in series so that
the power from the engine 8 as a motive power source is transmitted
by the differential motion portion 11 and the automatic ratio shift
portion 20 in that order, this is not restrictive. The transmission
mechanism 10 may also have a construction in which the power from
the engine 8 is transmitted by the automatic ratio shift portion 20
and the differential motion portion 11 in that order.
[0159] Besides, although in the foregoing embodiments, the
transmission mechanism 10 as a power transmission device is a
transmission mechanism in which the differential motion portion 11
and the automatic ratio shift portion 20 are connected in series
via the transmission member 18, this is not restrictive. The
invention is applicable to any power transmission device if the
power transmission device has a construction that includes a
function of performing electrical operation as the whole power
transmission device, and a function of performing, as the whole
power transmission device, the ratio shift on a principle that is
different from the principle of the ratio shift performed on the
basis of electrical differential motion. The differential motion
portion and the automatic ratio shift portion do not need to be
mechanically independent.
[0160] For example, the invention is also applicable to a
construction in which two planetary gear devices are interlinked by
their portions, and in which various rotating elements are linked
with an internal combustion engine, an electric motor, and driving
wheels so that power can be transmitted therebetween, and in which
the switching between the stepped ratio shift and the stepless
ratio shift can be performed by controlling the clutches or brakes
connected to the rotating elements of a planetary gear.
[0161] Besides, in the foregoing embodiments, the planetary gear
device is a single planetary structure, this is not restrictive.
For example, the planetary gear device may also be of a different
structure, such as a double-planetary structure, or the like.
[0162] While the invention has been described with reference to
example embodiments thereof, it is to be understood that the
invention is not limited to the described embodiments or
constructions. To the contrary, the invention is intended to cover
various modifications and equivalent arrangements. In addition,
while the various elements of the example embodiments are shown in
various combinations and configurations, other combinations and
configurations, including more, less or only a single element, are
also within the spirit and scope of the invention.
* * * * *